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\/\u003E\u003C\/head\u003E\u003Cbody\u003E\u003Cdiv class=\u0022panels-ajax-tab-panel panels-ajax-tab-panel-jnl-template-cob-tab-art\u0022\u003E\u003Cdiv class=\u0022panel-display panel-1col clearfix\u0022 \u003E\n \u003Cdiv class=\u0022panel-panel panel-col\u0022\u003E\n \u003Cdiv\u003E\u003Cdiv class=\u0022panel-pane pane-highwire-markup article-heading\u0022 \u003E\n \n \n \n \u003Cdiv class=\u0022pane-content\u0022\u003E\n \u003Cdiv class=\u0022highwire-markup\u0022\u003E\u003Cdiv xmlns=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022 id=\u0022content-block-markup\u0022 data-highwire-cite-ref-tooltip-instance=\u0022highwire_reflinks_tooltip\u0022 xmlns:xhtml=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022\u003E\u003Cdiv class=\u0022article fulltext-view\u0022\u003E\u003Cspan class=\u0022highwire-journal-article-marker-start\u0022\u003E\u003C\/span\u003E\u003Cdiv class=\u0022section abstract\u0022 id=\u0022abstract-1\u0022\u003E\u003Ch2\u003ESUMMARY\u003C\/h2\u003E\n \u003Cp id=\u0022p-1\u0022\u003EFlies rely heavily on visual feedback for several aspects of flight\ncontrol. As a fly approaches an object, the image projected across its retina\nexpands, providing the fly with visual feedback that can be used either to\ntrigger a collision-avoidance maneuver or a landing response. To determine how\na fly makes the decision to land on or avoid a looming object, we measured the\nbehaviors generated in response to an expanding image during tethered flight\nin a visual closed-loop flight arena. During these experiments, each fly\nvaried its wing-stroke kinematics to actively control the azimuth position of\na 15\u00b0\u00d715\u00b0 square within its visual field. Periodically, the\nsquare symmetrically expanded in both the horizontal and vertical directions.\nWe measured changes in the fly\u0027s wing-stroke amplitude and frequency in\nresponse to the expanding square while optically tracking the position of its\nlegs to monitor stereotyped landing responses. Although this stimulus could\nelicit both the landing responses and collision-avoidance reactions, separate\npathways appear to mediate the two behaviors. For example, if the square is in\nthe lateral portion of the fly\u0027s field of view at the onset of expansion, the\nfly increases stroke amplitude in one wing while decreasing amplitude in the\nother, indicative of a collision-avoidance maneuver. In contrast, frontal\nexpansion elicits an increase in wing-beat frequency and leg extension,\nindicative of a landing response. To further characterize the sensitivity of\nthese responses to expansion rate, we tested a range of expansion velocities\nfrom 100 to 10 000\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E. Differences in the latency of both the\ncollision-avoidance reactions and the landing responses with expansion rate\nsupported the hypothesis that the two behaviors are mediated by separate\npathways. To examine the effects of visual feedback on the magnitude and time\ncourse of the two behaviors, we presented the stimulus under open-loop\nconditions, such that the fly\u0027s response did not alter the position of the\nexpanding square. From our results we suggest a model that takes into account\nthe spatial sensitivities and temporal latencies of the collision-avoidance\nand landing responses, and is sufficient to schematically represent how the\nfly uses integration of motion information in deciding whether to turn or land\nwhen confronted with an expanding object.\u003C\/p\u003E\n \u003C\/div\u003E\u003Cul class=\u0022kwd-group KWD\u0022\u003E\u003Cli class=\u0022kwd\u0022\u003E\u003Ca href=\u0022\/keyword\/looming\u0022 class=\u0022hw-term hw-article-keyword hw-article-keyword-looming\u0022 rel=\u0022nofollow\u0022\u003Elooming\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003E\u003Ca href=\u0022\/keyword\/optic-flow\u0022 class=\u0022hw-term hw-article-keyword hw-article-keyword-optic-flow\u0022 rel=\u0022nofollow\u0022\u003Eoptic flow\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003E\u003Ca href=\u0022\/keyword\/saccades\u0022 class=\u0022hw-term hw-article-keyword hw-article-keyword-saccades\u0022 rel=\u0022nofollow\u0022\u003Esaccades\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003E\u003Ca href=\u0022\/search\/%20text_abstract_title%3Alanding%2Bresponse%20text_abstract_title_flags%3Amatch-phrase%20sort%3Apublication-date\u0022 class=\u0022hw-term hw-article-keyword hw-article-keyword-landing-response\u0022 rel=\u0022nofollow\u0022\u003Elanding response\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003E\u003Ca xmlns:default=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022 href=\u0022\/keyword\/drosophila-melanogaster\u0022 class=\u0022hw-term hw-article-keyword hw-article-keyword-drosophila-melanogaster\u0022 rel=\u0022nofollow\u0022\u003E\n \u003Cem xmlns:default=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022\u003EDrosophila melanogaster\u003C\/em\u003E\n \u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003E\u003Ca href=\u0022\/keyword\/collision-avoidance\u0022 class=\u0022hw-term hw-article-keyword hw-article-keyword-collision-avoidance\u0022 rel=\u0022nofollow\u0022\u003Ecollision avoidance\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003Cdiv class=\u0022section\u0022 id=\u0022sec-1\u0022\u003E\n \u003Ch2\u003EIntroduction\u003C\/h2\u003E\n \u003Cp id=\u0022p-2\u0022\u003EWhen searching for food, a flying animal must efficiently navigate through\nits environment, avoid obstacles and eventually alight on its desired target.\nThus, a common choice in any flight search algorithm is the decision about\nwhether to turn away from an approaching object or land on it. When exploring\ntheir environment, many flies use a series of straight-line flight segments\ninterspersed with rapid turns called saccades\n(\u003Ca id=\u0022xref-ref-6-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-6\u0022\u003ECollett and Land, 1975\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-30-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-30\u0022\u003ETammero and Dickinson, 2002\u003C\/a\u003E).\nWhile some saccades are spontaneously generated in the absence of any visual\ninput (\u003Ca id=\u0022xref-ref-18-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-18\u0022\u003EHeide, 1983\u003C\/a\u003E),\nreconstructions of optic flow patterns based upon the fly\u0027s motion through an\nartificial visual landscape suggest that image expansion plays a role in\ntriggering saccades (\u003Ca id=\u0022xref-ref-30-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-30\u0022\u003ETammero and\nDickinson, 2002\u003C\/a\u003E). However, approximations of image expansion have\nalso been shown to elicit leg extension in tethered flies, which is a motor\nresponse thought to represent a landing reflex\n(\u003Ca id=\u0022xref-ref-1-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-1\u0022\u003EBorst, 1986\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-15-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-15\u0022\u003EGoodman, 1960\u003C\/a\u003E). During\ntethered flight in the housefly \u003Cem\u003EMusca domestica\u003C\/em\u003E, leg extension was\naccompanied by a change in wing-stroke envelope and a decrease in forward\nthrust (\u003Ca id=\u0022xref-ref-5-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-5\u0022\u003EBorst and Bahde, 1988\u003C\/a\u003E).\nThus, as a pattern of visual motion indicative of approaching objects, image\nexpansion can elicit two potentially conflicting motor responses in the\nfly.\u003C\/p\u003E\n \u003Cp id=\u0022p-3\u0022\u003EDifferent aspects of the image expansion experienced by a fly might\nunderlie the decision about whether to saccade or land. First, the visual\nprocesses triggering landing and collision avoidance might have different\nsensitivities to the speed of image expansion. Second, the decision to saccade\nor land might depend upon differences in the spatial tuning of the two\nresponses. For example, the focus of image expansion that best activates each\nof the two behaviors might lie in different regions of visual field. Third,\ninformation from other sensory modalities, such as the presence of attractive\nodors, or the behavioral context, such as the length of the flight period\npreceding the decision, might bias the probability with which visual expansion\nelicits the two responses.\u003C\/p\u003E\n \u003Cp id=\u0022p-4\u0022\u003EThe purpose of these experiments is to determine which visual cues\navailable to the fly increase the probability of landing or collision\navoidance. We examine the influence of an expanding object on the fruit fly\n\u003Cem\u003EDrosophila melanogaster\u003C\/em\u003E, using a tethered-flight arena in which a\nfly\u0027s visual environment can be precisely controlled\n(\u003Ca id=\u0022xref-ref-9-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-9\u0022\u003EDickinson and Lighton, 1995\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-25-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-25\u0022\u003ELehmann and Dickinson, 1997\u003C\/a\u003E).\nWhen flying within tethered-flight simulators, flies (\u003Cem\u003EDrosophila\u003C\/em\u003E)\nexhibit rapid changes in wing kinematics and yaw torque that have been\ninterpreted as analogous to free-flight saccades\n(\u003Ca id=\u0022xref-ref-16-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-16\u0022\u003EG\u00f6tz et al., 1979\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-19-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-19\u0022\u003EHeide and G\u00f6tz, 1996\u003C\/a\u003E;\nHeisenberg and Wolf, \u003Ca id=\u0022xref-ref-20-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-20\u0022\u003E1979\u003C\/a\u003E,\n\u003Ca id=\u0022xref-ref-21-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-21\u0022\u003E1984\u003C\/a\u003E). Tethered flies also\ndemonstrate easily discernable leg extensions that are characteristic of the\nlanding response (\u003Ca id=\u0022xref-ref-1-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-1\u0022\u003EBorst, 1986\u003C\/a\u003E).\nIn these experiments, a change in wing stroke sending an object to the rear\nvisual field is considered a collision-avoidance response. Leg extension is\ninterpreted as a landing attempt. By examining the effect of both the retinal\nposition and rate of expansion of the stimulus on the landing and the\ncollision-avoidance responses, we show that although the stimulus features\nthat elicit each of these behaviors are similar, each must be processed by\nseparate circuits within the fly\u0027s brain.\u003C\/p\u003E\n \u003C\/div\u003E\u003Cdiv class=\u0022section\u0022 id=\u0022sec-2\u0022\u003E\n \u003Ch2\u003EMaterials and methods\u003C\/h2\u003E\n \u003Cdiv id=\u0022sec-3\u0022 class=\u0022subsection\u0022\u003E\n \u003Ch3\u003EAnimals\u003C\/h3\u003E\n \u003Cp id=\u0022p-5\u0022\u003EAll experiments were performed on 2- to 5-day-old female fruit flies,\n\u003Cem\u003EDrosophila melanogaster\u003C\/em\u003E (Meichen), from a laboratory culture\ndescended from 200 caught wild females. Flies were tethered with the body in a\nhovering posture at a pitch angle of 45\u00b0 from the vertical, as previously\ndescribed (\u003Ca id=\u0022xref-ref-25-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-25\u0022\u003ELehmann and Dickinson,\n1997\u003C\/a\u003E) and were allowed to recover for 1-2h. During this time, the\nflies were also dark-adapted, so as to increase their visual responses. Each\nset of stimulus presentations lasted between 15-30 min. Any individual that\nfailed to maintain flight for at least 15 min was not included in further\nanalysis. The final data set consisted of 41 h of total flight time measured\non 122 flies.\u003C\/p\u003E\n \u003C\/div\u003E\n \u003Cdiv id=\u0022sec-4\u0022 class=\u0022subsection\u0022\u003E\n \u003Ch3\u003EData collection\u003C\/h3\u003E\n \u003Cp id=\u0022p-6\u0022\u003EThe flies were tethered in a virtual-reality flight arena described in\nprevious studies (\u003Ca id=\u0022xref-ref-9-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-9\u0022\u003EDickinson and Lighton,\n1995\u003C\/a\u003E; \u003Ca id=\u0022xref-ref-25-3\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-25\u0022\u003ELehmann and Dickinson,\n1997\u003C\/a\u003E) (\u003Ca id=\u0022xref-fig-1-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F1\u0022\u003EFig. 1\u003C\/a\u003E). The\nstroke amplitudes of both wings and the wing-beat frequency were tracked\noptically and sampled at 1000 Hz using a data acquisition board (National\nInstruments) and software written in MATLAB (Mathworks). The difference\nbetween the left and right wing-beat amplitudes, a signal strongly correlated\nto the torque generated by the fly about its yaw axis, was fed back to the\narena controller and used to control the angular velocity of a\n15\u00b0\u00d715\u00b0 black square. Thus, the fly actively controlled the\nazimuthal position of the square. A sinusoidal bias with a frequency of 0.01\nHz and a maximum amplitude of approximately 75\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E was then\nadded to the feedback signal to make it more difficult for the flies to fixate\nthe square within the frontal region of the visual field. At 5 s intervals,\nthe fly was presented with an expansion stimulus in which both dimensions of\nthe square increased at a constant rate. Thus, we did not systematically map\nthe response to the expansion stimulus in different regions of the visual\nfield. Instead, the azimuthal position of the square at the onset of expansion\nwas determined by the fly, which was actively controlling the position of the\nsquare throughout the experiment. However, because the closed-loop design\nproduces such long flight sequences, the positions of the expanding stimulus\ndensely covered the entire range along the azimuth.\u003C\/p\u003E\n \u003Cp id=\u0022p-7\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F1\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F1.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022Schematized experimental setup for measuring a fly\u0027s response to image expansion. During tethered flight, the fly\u0027s wingstroke amplitude and frequency are measured by optically tracking the shadows cast from an infra-red (IR) diode by each of the wings on an optical wing-beat analyzer (Dickinson and Lighton, 1995; Lehmann and Dickinson, 1997). During closed-loop experiments, the difference between the amplitude of each wing stroke controls the visual display, allowing the fly to orient actively toward the position of the 15\u0026#xB0;\u0026#xD7;15\u0026#xB0; square. At periodic intervals, the square symmetrically expands, eliciting a behavioral response.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1711143943\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;Schematized experimental setup for measuring a fly\u0027s response to image expansion. During tethered flight, the fly\u0027s wingstroke amplitude and frequency are measured by optically tracking the shadows cast from an infra-red (IR) diode by each of the wings on an optical wing-beat analyzer (Dickinson and Lighton, 1995; Lehmann and Dickinson, 1997). During closed-loop experiments, the difference between the amplitude of each wing stroke controls the visual display, allowing the fly to orient actively toward the position of the 15\u0026#xB0;\u0026#xD7;15\u0026#xB0; square. At periodic intervals, the square symmetrically expands, eliciting a behavioral response.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 1.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F1.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 1.\u0022 src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F1.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F1.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 1.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F1.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1076113\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022 xmlns:xhtml=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 1.\u003C\/span\u003E \n \u003Cp id=\u0022p-8\u0022 class=\u0022first-child\u0022\u003ESchematized experimental setup for measuring a fly\u0027s response to image\nexpansion. During tethered flight, the fly\u0027s wingstroke amplitude and\nfrequency are measured by optically tracking the shadows cast from an\ninfra-red (IR) diode by each of the wings on an optical wing-beat analyzer\n(\u003Ca id=\u0022xref-ref-9-3\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-9\u0022\u003EDickinson and Lighton, 1995\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-25-4\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-25\u0022\u003ELehmann and Dickinson, 1997\u003C\/a\u003E).\nDuring closed-loop experiments, the difference between the amplitude of each\nwing stroke controls the visual display, allowing the fly to orient actively\ntoward the position of the 15\u00b0\u00d715\u00b0 square. At periodic\nintervals, the square symmetrically expands, eliciting a behavioral\nresponse.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-9\u0022\u003EBecause each light-emitting diode (LED) of the arena subtended an angle of\n5\u00b0, expanding the square symmetrically required a series of 10\u00b0 jumps\nat periodic intervals. The rate of expansion was determined by the constant\ninterval between 10\u00b0 jumps. Ten intervals were used, of 100, 70, 40, 30,\n20, 10, 7, 5, 2 and 1 ms, which led to expansion velocities of 100, 143, 333,\n250, 500, 1000, 1430, 2000, 5000 and 10000\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E, respectively.\nThe square expanded until it reached a width of 115\u00b0 and remained at that\nwidth for 800 ms, after which it instantaneously returned to a width of\n15\u00b0 until the next presentation. 7-15 flies were tested at each rate of\nexpansion, with each stimulus of a given expansion rate presented to an\nindividual 150-350 times. The stimulus provided only a simplified version of\nthe optic flow that a freely flying animal would encounter as it flies toward\na stationary object. For example, in our experiments the expansion rate was\nlinear and constant, whereas in free flight the rate of expansion would\nincrease as the animal moves closer to the object (see\n\u003Ca id=\u0022xref-ref-13-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-13\u0022\u003EGabbiani et al., 1999\u003C\/a\u003E). Thus,\nour stimulus would simulate a deceleration as the fly approached an object.\nTechnical limitations due to the low resolution of the visual display and the\nmethod of programming the expansion on it prevented a more naturalistic rate\nof expansion.\u003C\/p\u003E\n \u003Cp id=\u0022p-10\u0022\u003ETo measure the fly\u0027s landing response, a CCD camera was focused on the fly\nand connected to a closed circuit monitor. A photovoltaic sensor was\npositioned on the monitor beneath the image of the fly such that extension of\nthe prothoracic legs would generate an increase in luminance, as sensed by the\ndiode. The signal from the photovoltaic chip was amplified by a factor of 20\nand low-pass-filtered at 10 Hz using a programmable signal conditioner\n(CyberAmp 380, Axon Instruments).\u003C\/p\u003E\n \u003C\/div\u003E\n \u003Cdiv id=\u0022sec-5\u0022 class=\u0022subsection\u0022\u003E\n \u003Ch3\u003ESignal conditioning\u003C\/h3\u003E\n \u003Cp id=\u0022p-11\u0022\u003EThe raw amplitude and frequency signals from each wing were conditioned for\nanalysis in the following manner. First, the average wing-beat amplitude\nduring the 200 ms preceding the presentation of the stimulus was subtracted\nfrom the subsequent response. Each wing-beat amplitude signal was then\nsmoothed using a low-pass Butterworth filter with a cut-off frequency of 40\nHz. The signals were then downsampled by a factor of 5 to a rate of 200 Hz. To\ncorrect for slight differences in each fly\u0027s position over the wing-beat\nsensor, the standard deviations of the wing-beat amplitudes from the 200 ms\n(an interval representing roughly 40 wing-beat cycles) preceding each stimulus\npresentation was calculated over all flies. The standard deviation for each\nindividual fly was then normalized to this value. To condition the wing-beat\nfrequency, the mean value of the 200 ms pre-stimulus period was subtracted for\neach trace. After that, each value in the trace was divided by the average\npre-stimulus value. Thus, frequency is represented as a percentage of the\nbaseline level. The wing-beat frequency was then filtered and down-sampled in\na manner identical to the wing-beat signals.\u003C\/p\u003E\n \u003C\/div\u003E\n \u003C\/div\u003E\u003Cdiv class=\u0022section\u0022 id=\u0022sec-6\u0022\u003E\n \u003Ch2\u003EResults\u003C\/h2\u003E\n \u003Cp id=\u0022p-12\u0022\u003EAs illustrated in \u003Ca id=\u0022xref-fig-2-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003EFig. 2\u003C\/a\u003E,\nexpansion of the square to which the flies fixated elicited changes in both\nstroke kinematics and leg motion. The expression of these two behavioral\nresponses varied with the position of the object at the start of expansion.\nFor example, if the expanding square was positioned in the lateral visual\nfield at the onset of expansion, the stroke amplitude of the inside wing (that\nnearest to the stimulus) increased while that of the outside wing decreased\n(\u003Ca id=\u0022xref-fig-2-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003EFig. 2A,C\u003C\/a\u003E). These changes in\nwing-beat amplitude caused the object to move caudally in the field of view\n(\u003Ca id=\u0022xref-fig-2-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003EFig. 2A,C\u003C\/a\u003E), consistent with a\ncollision-avoidance response. In contrast, when the square was positioned in\nthe fly\u0027s frontal visual field of view at the onset of expansion, the changes\nin wing-beat amplitude were comparatively small, and had little effect on the\nposition of the stimulus (\u003Ca id=\u0022xref-fig-2-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003EFig.\n2B\u003C\/a\u003E). Wing-beat frequency also increased in response to the\nexpanding square, with the largest increase occurring when the square expanded\ndirectly in front of the fly. Although the exact role of the increase in\nwing-beat frequency accompanying the landing response is unknown, it is\nthought to represent the fly\u0027s attempt to decelerate or generate an upwards\npitching motion. Frontal expansion also elicited leg motion\n(\u003Ca id=\u0022xref-fig-2-5\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003EFig. 2B\u003C\/a\u003E), indicative of a\nstereotyped landing response (\u003Ca id=\u0022xref-ref-1-3\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-1\u0022\u003EBorst,\n1986\u003C\/a\u003E; \u003Ca id=\u0022xref-ref-15-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-15\u0022\u003EGoodman,\n1960\u003C\/a\u003E).\u003C\/p\u003E\n \u003Cp id=\u0022p-13\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F2\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F2.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022Wing and leg responses elicited by an expanding object (recorded as V). In response to a square expanding at a rate of 500\u0026#xB0; s-1, the fly generates both wing and leg responses. The time course of stimulus expansion is shown in the bottom traces. If the object is displaced laterally, the inside wing (that on the side of the stimulus) shows a transient increase in wing-beat amplitude, while the outside wing decreases in stroke amplitude. (A) If the object is to the left of the fly, the left wing-beat amplitude (blue) increases while the right wing-stroke amplitude (red) decreases, causing the square to move to the rear of the fly\u0027s field of view. In contrast, expansion of centrally positioned objects elicits smaller changes in wing motion, causing little change in the position of the object (B). Image expansion in the frontal field of view elicits leg extension as well as an increase in wing-beat frequency, both indicative of a landing response. When the stimulus is to the right of fly, the sign of the change in both wing-beat responses is reversed, again causing the object to move to the rear of the fly\u0027s field of view (C). Laterally positioned image expansion elicits a transient increase in wing-beat frequency but does not evoke a leg response.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1711143943\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;Wing and leg responses elicited by an expanding object (recorded as V). In response to a square expanding at a rate of 500\u0026#xB0; s-1, the fly generates both wing and leg responses. The time course of stimulus expansion is shown in the bottom traces. If the object is displaced laterally, the inside wing (that on the side of the stimulus) shows a transient increase in wing-beat amplitude, while the outside wing decreases in stroke amplitude. (A) If the object is to the left of the fly, the left wing-beat amplitude (blue) increases while the right wing-stroke amplitude (red) decreases, causing the square to move to the rear of the fly\u0027s field of view. In contrast, expansion of centrally positioned objects elicits smaller changes in wing motion, causing little change in the position of the object (B). Image expansion in the frontal field of view elicits leg extension as well as an increase in wing-beat frequency, both indicative of a landing response. When the stimulus is to the right of fly, the sign of the change in both wing-beat responses is reversed, again causing the object to move to the rear of the fly\u0027s field of view (C). Laterally positioned image expansion elicits a transient increase in wing-beat frequency but does not evoke a leg response.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 2.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F2.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 2.\u0022 src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F2.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F2.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 2.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F2.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1076119\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 2.\u003C\/span\u003E \n \u003Cp id=\u0022p-14\u0022 class=\u0022first-child\u0022\u003EWing and leg responses elicited by an expanding object (recorded as V). In\nresponse to a square expanding at a rate of 500\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E, the fly\ngenerates both wing and leg responses. The time course of stimulus expansion\nis shown in the bottom traces. If the object is displaced laterally, the\ninside wing (that on the side of the stimulus) shows a transient increase in\nwing-beat amplitude, while the outside wing decreases in stroke amplitude. (A)\nIf the object is to the left of the fly, the left wing-beat amplitude (blue)\nincreases while the right wing-stroke amplitude (red) decreases, causing the\nsquare to move to the rear of the fly\u0027s field of view. In contrast, expansion\nof centrally positioned objects elicits smaller changes in wing motion,\ncausing little change in the position of the object (B). Image expansion in\nthe frontal field of view elicits leg extension as well as an increase in\nwing-beat frequency, both indicative of a landing response. When the stimulus\nis to the right of fly, the sign of the change in both wing-beat responses is\nreversed, again causing the object to move to the rear of the fly\u0027s field of\nview (C). Laterally positioned image expansion elicits a transient increase in\nwing-beat frequency but does not evoke a leg response.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-15\u0022\u003EDuring free flight, flies avoid collisions using rapid saccadic turns, the\nmagnitude of which are independent of the fly\u0027s angle of approach\n(\u003Ca id=\u0022xref-ref-30-3\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-30\u0022\u003ETammero and Dickinson, 2002\u003C\/a\u003E).\nTo determine whether the magnitude of collision-avoidance responses in\ntethered flight varied with the retinal position of the expanding object,\nindividual wing-beat amplitude responses for each fly were grouped by stimulus\nposition at the onset of expansion (\u003Ca id=\u0022xref-fig-3-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F3\u0022\u003EFig.\n3A\u003C\/a\u003E). Although the size of the responses varied from presentation\nto presentation, the average responses elicited by expansion at a lateral\nposition were larger than those seen at frontal and caudal positions. This\ndependency on the position of the expanding stimulus was consistent across\nanimals (\u003Ca id=\u0022xref-fig-3-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F3\u0022\u003EFig. 3B\u003C\/a\u003E). The maximum\nchange in wing-beat amplitude for each wing, the wing-beat frequency, and the\nchange in the difference between left and right wing-beat amplitudes following\nthe expansion stimulus, are plotted against stimulus position in\n\u003Ca id=\u0022xref-fig-4-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003EFig. 4\u003C\/a\u003E. The change in wing-beat\namplitude for both the left and right wings varies sinusoidally with stimulus\nposition, as does the maximum change in their difference\n(\u003Ca id=\u0022xref-fig-4-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003EFig. 4A,B\u003C\/a\u003E). The largest change\nin wing-beat frequency occurs when in the image expands frontally, with a\ngradual decay for more lateral stimulus positions. Like wing-beat frequency,\nthe probability of the expanding object eliciting a landing response is\ngreatest for frontal expansion (\u003Ca id=\u0022xref-fig-4-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003EFig.\n4C,D\u003C\/a\u003E). The two behaviors, changes in wing motion and the landing\nresponse, are not mutually exclusive. Stimulus expansion over a range of\nfrontolateral positions can elicit both a landing response and a\ncollision-avoidance response.\u003C\/p\u003E\n \u003Cp id=\u0022p-16\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F3\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F3.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022The effect of stimulus position on behavioral response. (A) A single fly\u0027s response to multiple presentations of a square expanding at 500\u0026#xB0; s-1 varies with stimulus position. Each individual trace shows the response of the left (blue) and right (red) wing to a presentation of the expansion stimulus. The bold and dotted lines represent the mean response\u0026#xB1; S.D. for stimuli between given positions. Expansion in lateral positions evokes the largest change in wing-beat amplitude (WBA), with responses decaying for more frontal and caudal stimulus presentations. (B) Results from multiple flies. The individual traces are the mean left and right wing-beat amplitude response taken from 12 individuals. The bold and dotted lines represent the mean \u0026#xB1; S.D., respectively, across individuals.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1711143943\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;The effect of stimulus position on behavioral response. (A) A single fly\u0027s response to multiple presentations of a square expanding at 500\u0026#xB0; s-1 varies with stimulus position. Each individual trace shows the response of the left (blue) and right (red) wing to a presentation of the expansion stimulus. The bold and dotted lines represent the mean response\u0026#xB1; S.D. for stimuli between given positions. Expansion in lateral positions evokes the largest change in wing-beat amplitude (WBA), with responses decaying for more frontal and caudal stimulus presentations. (B) Results from multiple flies. The individual traces are the mean left and right wing-beat amplitude response taken from 12 individuals. The bold and dotted lines represent the mean \u0026#xB1; S.D., respectively, across individuals.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 3.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F3.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 3.\u0022 src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F3.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F3.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 3.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F3.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1076121\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 3.\u003C\/span\u003E \n \u003Cp id=\u0022p-17\u0022 class=\u0022first-child\u0022\u003EThe effect of stimulus position on behavioral response. (A) A single fly\u0027s\nresponse to multiple presentations of a square expanding at 500\u00b0\ns\u003Csup\u003E-1\u003C\/sup\u003E varies with stimulus position. Each individual trace shows the\nresponse of the left (blue) and right (red) wing to a presentation of the\nexpansion stimulus. The bold and dotted lines represent the mean response\u00b1\n S.D. for stimuli between given positions. Expansion in lateral\npositions evokes the largest change in wing-beat amplitude (WBA), with\nresponses decaying for more frontal and caudal stimulus presentations. (B)\nResults from multiple flies. The individual traces are the mean left and right\nwing-beat amplitude response taken from 12 individuals. The bold and dotted\nlines represent the mean \u00b1 S.D., respectively, across individuals.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-18\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F4\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F4.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022Collision-avoidance and landing responses vary with the position of stimulus expansion. (A) The maximum change in value of the wing-beat amplitude (WBA) from the baseline level of both the right (R; red) and left (L; blue) wings varies sinusoidally with the position of the stimulus. (B) A similar variation occurs for the maximum change in the difference between the left and right wing signals. (C) The percentage change in wing-beat frequency (WBF) was largest for expansion occurring in front of the fly and decreases slightly for lateral positions. (D) The probability of eliciting a landing response is greatest for frontal positions. Data points represent the mean value of maximum change \u0026#xB1; S.E.M. The number of trials at each position is different because it was determined by where the fly happened to position the object at the onset of expansion. Data are taken from 300 presentations of a square expanding at a rate of 500\u0026#xB0; s-1 to a single fly.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1711143943\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;Collision-avoidance and landing responses vary with the position of stimulus expansion. (A) The maximum change in value of the wing-beat amplitude (WBA) from the baseline level of both the right (R; red) and left (L; blue) wings varies sinusoidally with the position of the stimulus. (B) A similar variation occurs for the maximum change in the difference between the left and right wing signals. (C) The percentage change in wing-beat frequency (WBF) was largest for expansion occurring in front of the fly and decreases slightly for lateral positions. (D) The probability of eliciting a landing response is greatest for frontal positions. Data points represent the mean value of maximum change \u0026#xB1; S.E.M. The number of trials at each position is different because it was determined by where the fly happened to position the object at the onset of expansion. Data are taken from 300 presentations of a square expanding at a rate of 500\u0026#xB0; s-1 to a single fly.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 4.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F4.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 4.\u0022 src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F4.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F4.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 4.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F4.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1076123\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 4.\u003C\/span\u003E \n \u003Cp id=\u0022p-19\u0022 class=\u0022first-child\u0022\u003ECollision-avoidance and landing responses vary with the position of\nstimulus expansion. (A) The maximum change in value of the wing-beat amplitude\n(WBA) from the baseline level of both the right (R; red) and left (L; blue)\nwings varies sinusoidally with the position of the stimulus. (B) A similar\nvariation occurs for the maximum change in the difference between the left and\nright wing signals. (C) The percentage change in wing-beat frequency (WBF) was\nlargest for expansion occurring in front of the fly and decreases slightly for\nlateral positions. (D) The probability of eliciting a landing response is\ngreatest for frontal positions. Data points represent the mean value of\nmaximum change \u00b1 S.E.M. The number of trials at each position is\ndifferent because it was determined by where the fly happened to position the\nobject at the onset of expansion. Data are taken from 300 presentations of a\nsquare expanding at a rate of 500\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E to a single fly.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-20\u0022\u003EBecause the immediate threat of collision with rapidly approaching objects\nis greater than that with objects moving more slowly, the fly\u0027s response to\nimage expansion might vary with the rate of expansion. To examine how\ndifferent expansion rates affect the collision-avoidance and landing\nresponses, we measured behavioral changes for squares expanding at varying\nrates (\u003Ca id=\u0022xref-fig-5-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F5\u0022\u003EFig. 5\u003C\/a\u003E). Using the fact\nthat the difference between the left and right wing-beat amplitudes varies\nsinusoidally with stimulus position, we quantified the magnitude of the\ncollision-avoidance response at each expansion rate by calculating the\namplitude of a sine wave fitted to the position-response curve for each fly.\nTo quantify the landing response at each expansion rate, we determined the\nwidth of the range of stimulus positions in which the probability of landing\nresponse was greater than 0.5 for each fly. We normalized the response by\ndividing the sine amplitudes and the landing response widths measured for each\nrate of expansion by the maximum mean responses\n(\u003Ca id=\u0022xref-fig-6-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F6\u0022\u003EFig. 6\u003C\/a\u003E). Although the\nsensitivity of the two behaviors to expansion rate is similar, the\ncollision-avoidance response is more broadly tuned. Whereas the two behaviors\nare maximally activated at an expansion rate of approximately 1000\u00b0\ns\u003Csup\u003E-1\u003C\/sup\u003E, the collision-avoidance response displays a greater\nsensitivity to both faster and slower expansion than the landing response.\u003C\/p\u003E\n \u003Cp id=\u0022p-21\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F5\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F5.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022The effects of expansion rate on collision-avoidance and landing responses. Each column represents the wing-beat amplitude (WBA), and the landing response probabilities plotted against stimulus position as described in Fig. 4 for a different rate of expansion. The functions shown in Fig. 4 were determined for each fly, with each data point representing the mean \u0026#xB1; S.E.M. taken over all the flies. The numbers of flies tested were 8, 11, 11, 8, 12, 11, 8, 10, 7, 7 and 5 for expansion rate in ascending order (starting at 100\u0026#xB0; s-1). The total numbers of stimulus presentations, again in ascending order, were 1945, 2905, 2584, 1746, 3237, 2529, 216, 2223, 1771, 1391 and 1132. The sinusoidal shape of the wing-stroke amplitude responses holds for all expansion rates, with the amplitude of the response being largest for an expansion rate of 1000\u0026#xB0; s-1. The probability of landing is high over the greatest range of positions at an expansion rate of 1430\u0026#xB0; s-1. L, left; R, right; WBF, wing-beat frequency.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1711143943\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;The effects of expansion rate on collision-avoidance and landing responses. Each column represents the wing-beat amplitude (WBA), and the landing response probabilities plotted against stimulus position as described in Fig. 4 for a different rate of expansion. The functions shown in Fig. 4 were determined for each fly, with each data point representing the mean \u0026#xB1; S.E.M. taken over all the flies. The numbers of flies tested were 8, 11, 11, 8, 12, 11, 8, 10, 7, 7 and 5 for expansion rate in ascending order (starting at 100\u0026#xB0; s-1). The total numbers of stimulus presentations, again in ascending order, were 1945, 2905, 2584, 1746, 3237, 2529, 216, 2223, 1771, 1391 and 1132. The sinusoidal shape of the wing-stroke amplitude responses holds for all expansion rates, with the amplitude of the response being largest for an expansion rate of 1000\u0026#xB0; s-1. The probability of landing is high over the greatest range of positions at an expansion rate of 1430\u0026#xB0; s-1. L, left; R, right; WBF, wing-beat frequency.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 5.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F5.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 5.\u0022 src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F5.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F5.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 5.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F5.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1076125\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 5.\u003C\/span\u003E \n \u003Cp id=\u0022p-22\u0022 class=\u0022first-child\u0022\u003EThe effects of expansion rate on collision-avoidance and landing responses.\nEach column represents the wing-beat amplitude (WBA), and the landing response\nprobabilities plotted against stimulus position as described in\n\u003Ca id=\u0022xref-fig-4-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003EFig. 4\u003C\/a\u003E for a different rate of\nexpansion. The functions shown in \u003Ca id=\u0022xref-fig-4-5\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003EFig.\n4\u003C\/a\u003E were determined for each fly, with each data point representing\nthe mean \u00b1 S.E.M. taken over all the flies. The numbers of flies tested\nwere 8, 11, 11, 8, 12, 11, 8, 10, 7, 7 and 5 for expansion rate in ascending\norder (starting at 100\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E). The total numbers of stimulus\npresentations, again in ascending order, were 1945, 2905, 2584, 1746, 3237,\n2529, 216, 2223, 1771, 1391 and 1132. The sinusoidal shape of the wing-stroke\namplitude responses holds for all expansion rates, with the amplitude of the\nresponse being largest for an expansion rate of 1000\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E. The\nprobability of landing is high over the greatest range of positions at an\nexpansion rate of 1430\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E. L, left; R, right; WBF, wing-beat\nfrequency.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-23\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F6\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F6.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022Summary of changes in collision-avoidance and landing responses with rate of image expansion. The collision-avoidance response for a given expansion rate (open circles) is the sinusoid amplitude best fitting the maximum change in the difference between wing-beat amplitudes (see Fig. 5, second row), normalized by the maximum mean amplitude. The width of the range of positions for which the probability of landing is greater than 0.5 characterizes the landing response for a given expansion rate (filled circles). This response is normalized by the maximum mean width value. Values are means \u0026#xB1; S.E.M. for each fly.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1711143943\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;Summary of changes in collision-avoidance and landing responses with rate of image expansion. The collision-avoidance response for a given expansion rate (open circles) is the sinusoid amplitude best fitting the maximum change in the difference between wing-beat amplitudes (see Fig. 5, second row), normalized by the maximum mean amplitude. The width of the range of positions for which the probability of landing is greater than 0.5 characterizes the landing response for a given expansion rate (filled circles). This response is normalized by the maximum mean width value. Values are means \u0026#xB1; S.E.M. for each fly.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 6.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F6.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 6.\u0022 src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F6.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F6.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 6.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F6.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1076127\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 6.\u003C\/span\u003E \n \u003Cp id=\u0022p-24\u0022 class=\u0022first-child\u0022\u003ESummary of changes in collision-avoidance and landing responses with rate\nof image expansion. The collision-avoidance response for a given expansion\nrate (open circles) is the sinusoid amplitude best fitting the maximum change\nin the difference between wing-beat amplitudes (see\n\u003Ca id=\u0022xref-fig-5-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F5\u0022\u003EFig. 5\u003C\/a\u003E, second row), normalized\nby the maximum mean amplitude. The width of the range of positions for which\nthe probability of landing is greater than 0.5 characterizes the landing\nresponse for a given expansion rate (filled circles). This response is\nnormalized by the maximum mean width value. Values are means \u00b1 S.E.M.\nfor each fly.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-25\u0022\u003EA previous study showed that collision-avoidance saccades occurring during\nfree flight are of constant magnitude, suggesting a pre-programmed motor\nresponse (\u003Ca id=\u0022xref-ref-30-4\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-30\u0022\u003ETammero and Dickinson,\n2002\u003C\/a\u003E). In contrast, the amplitude of collision-avoidance responses\nduring tethered flight varied with both stimulus position and expansion\nvelocity. To examine the effect of expansion speed on the time course of the\ncollision-avoidance response, we plotted the difference between the left and\nright wing-beat amplitudes for stimuli of varying rates of expansion occurring\nat three locations (\u003Ca id=\u0022xref-fig-7-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F7\u0022\u003EFig. 7\u003C\/a\u003E).\nFor stimuli in each location, both the duration and amplitude of the response\nrose with the rate of expansion to a maximum at 1000\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E and\nfell off for faster rates. The influence of stimulus position on the response\nwas small when compared to the effects of expansion rate.\u003C\/p\u003E\n \u003Cp id=\u0022p-26\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F7\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F7.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022Effect of stimulus position and expansion rate on the time course of the wing response. Responses to stimuli presented within \u0026#xB1; 10\u0026#xB0; of the position were pooled. Each trace represents the mean \u0026#xB1; S.D. (shaded area) of the average responses taken from multiple flies. The time course of the responses does not vary with stimulus position but does vary greatly with rate of expansion. The number of flies at each expansion rate is given in Fig. 5. L, left; R, right.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1711143943\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;Effect of stimulus position and expansion rate on the time course of the wing response. Responses to stimuli presented within \u0026#xB1; 10\u0026#xB0; of the position were pooled. Each trace represents the mean \u0026#xB1; S.D. (shaded area) of the average responses taken from multiple flies. The time course of the responses does not vary with stimulus position but does vary greatly with rate of expansion. The number of flies at each expansion rate is given in Fig. 5. L, left; R, right.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 7.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F7.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 7.\u0022 src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F7.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F7.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 7.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F7.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1076129\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 7.\u003C\/span\u003E \n \u003Cp id=\u0022p-27\u0022 class=\u0022first-child\u0022\u003EEffect of stimulus position and expansion rate on the time course of the\nwing response. Responses to stimuli presented within \u00b1 10\u00b0 of the\nposition were pooled. Each trace represents the mean \u00b1 S.D. (shaded\narea) of the average responses taken from multiple flies. The time course of\nthe responses does not vary with stimulus position but does vary greatly with\nrate of expansion. The number of flies at each expansion rate is given in\n\u003Ca id=\u0022xref-fig-5-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F5\u0022\u003EFig. 5\u003C\/a\u003E. L, left; R, right.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-28\u0022\u003EIn addition to influencing response amplitude, variation in stimulus\nposition and rate of expansion might also affect the delay between the start\nof expansion and the onset of the response. In\n\u003Ca id=\u0022xref-fig-8-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig. 8A,B\u003C\/a\u003E, the latency from the\nstart of expansion to the onset of both the collision-avoidance and landing\nresponses is plotted. The latency of the collision-avoidance response shows a\nrelatively constant value of approximately 50 ms for stimulus positions\nbetween \u00b150\u00b0 and \u00b1130\u00b0, but increases for more frontal\nand caudal positions. In contrast, the landing response shows a nearly\nconstant delay of approximately 150 ms at all retinal positions where\nexpansion can trigger a landing response. Thus, whereas the probability of\ngenerating a landing response does depend on stimulus position, the latency of\nthe landing response does not. To examine the effect of expansion rate on\nresponse delay, the minimum latencies for the collision-avoidance and landing\nresponses were plotted against rate of stimulus expansion\n(\u003Ca id=\u0022xref-fig-8-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig. 8C\u003C\/a\u003E). Minimum landing\nresponse latency falls asymptotically from a value of 300 ms at 100\u00b0\ns\u003Csup\u003E-1\u003C\/sup\u003E to a value of 100 ms at rates of 1000\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E and\nhigher. In contrast, the minimum collision-avoidance delay shows a relatively\nconstant value of approximately 50 ms at all but the lowest expansion\nrates.\u003C\/p\u003E\n \u003Cp id=\u0022p-29\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F8\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F8.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022Collision-avoidance and landing response latencies depend on stimulus position and expansion rate. Latency is measured as the time interval between the onset of image expansion and the initiation of the landing or collision-avoidance response. (A) Latency in response to expansion at a rate of 500\u0026#xB0; s-1 is relatively constant over lateral portions of the fly\u0027s field of view and increases for positions to the front and rear. Data points represent mean latency \u0026#xB1; S.E.M. for 12 flies. (B) Landing response latency to a square expanding at 500\u0026#xB0; s-1 is constant at the stimulus positions at which landing response probability is high. At this expansion rate, the collision-avoidance latency is approximately half that of the landing response. (C) Response latencies plotted as a function of expansion rate. For a given rate of expansion, the minimum of the mean delay functions (such as the two plotted above) was determined. Filled circles represent the minimum mean delay in the landing response, while empty circles represent the minimum mean delay of the collision-avoidance response. The landing response latency decreases with the rate of expansion, whereas for most expansion rates the delay of the collision-avoidance response is constant.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1711143943\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;Collision-avoidance and landing response latencies depend on stimulus position and expansion rate. Latency is measured as the time interval between the onset of image expansion and the initiation of the landing or collision-avoidance response. (A) Latency in response to expansion at a rate of 500\u0026#xB0; s-1 is relatively constant over lateral portions of the fly\u0027s field of view and increases for positions to the front and rear. Data points represent mean latency \u0026#xB1; S.E.M. for 12 flies. (B) Landing response latency to a square expanding at 500\u0026#xB0; s-1 is constant at the stimulus positions at which landing response probability is high. At this expansion rate, the collision-avoidance latency is approximately half that of the landing response. (C) Response latencies plotted as a function of expansion rate. For a given rate of expansion, the minimum of the mean delay functions (such as the two plotted above) was determined. Filled circles represent the minimum mean delay in the landing response, while empty circles represent the minimum mean delay of the collision-avoidance response. The landing response latency decreases with the rate of expansion, whereas for most expansion rates the delay of the collision-avoidance response is constant.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 8.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F8.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 8.\u0022 src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F8.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F8.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 8.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F8.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1076131\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 8.\u003C\/span\u003E \n \u003Cp id=\u0022p-30\u0022 class=\u0022first-child\u0022\u003ECollision-avoidance and landing response latencies depend on stimulus\nposition and expansion rate. Latency is measured as the time interval between\nthe onset of image expansion and the initiation of the landing or\ncollision-avoidance response. (A) Latency in response to expansion at a rate\nof 500\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E is relatively constant over lateral portions of the\nfly\u0027s field of view and increases for positions to the front and rear. Data\npoints represent mean latency \u00b1 S.E.M. for 12 flies. (B) Landing\nresponse latency to a square expanding at 500\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E is constant\nat the stimulus positions at which landing response probability is high. At\nthis expansion rate, the collision-avoidance latency is approximately half\nthat of the landing response. (C) Response latencies plotted as a function of\nexpansion rate. For a given rate of expansion, the minimum of the mean delay\nfunctions (such as the two plotted above) was determined. Filled circles\nrepresent the minimum mean delay in the landing response, while empty circles\nrepresent the minimum mean delay of the collision-avoidance response. The\nlanding response latency decreases with the rate of expansion, whereas for\nmost expansion rates the delay of the collision-avoidance response is\nconstant.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-31\u0022\u003EIn the experiments described, each fly controlled the position of the\nsquare both before and during stimulus expansion. Therefore, the animal\u0027s\nresponse to the stimulus altered the expansion to which it was subject. To\ndetermine if this closed-loop implementation affected the behavioral\nresponses, we presented expansion stimuli under open-loop conditions in which\nthe fly\u0027s behavior had no impact on the position of the stimulus. A comparison\nof the open- and closed-loop responses for stimuli with identical expansion\nrates is depicted in \u003Ca id=\u0022xref-fig-9-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F9\u0022\u003EFig. 9\u003C\/a\u003E.\nInstead of varying sinusoidally with stimulus position, the relationship\nbetween stimulus position and the difference in the left and right wing beat\nsignals is better approximated by a square wave or a sigmoid in the open-loop\ncase (\u003Ca id=\u0022xref-fig-9-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F9\u0022\u003EFig. 9A\u003C\/a\u003E). In addition,\nthe probability of the landing response is slightly reduced compared with the\nclosed-loop case (\u003Ca id=\u0022xref-fig-9-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F9\u0022\u003EFig. 9B\u003C\/a\u003E). The\nlatencies of the landing and collision-avoidance responses are similar under\nclosed- and open-loop conditions, although the landing response delay is\nslightly longer following an open-loop presentation\n(\u003Ca id=\u0022xref-fig-9-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F9\u0022\u003EFig. 9C,D\u003C\/a\u003E). The individual\nwing responses follow similar time courses\n(\u003Ca id=\u0022xref-fig-10-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F10\u0022\u003EFig. 10\u003C\/a\u003E), although the\nresponses in both wings are larger in the open-loop case.\u003C\/p\u003E\n \u003Cp id=\u0022p-32\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F9\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F9.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022Open-loop versus closed-loop responses to image expansion. (A) During open-loop presentation the position of the square was controlled externally, as opposed to the closed-loop paradigm in which the fly maintains control over the position of the square. The closed-loop wing responses (filled circles) are repeated from Fig. 4. The open-loop responses (open circles), also generated in response to an expansion at a rate of 500\u0026#xB0; s-1, vary roughly with stimulus position as a square wave, in contrast to the open-loop responses, which vary sinusoidally. Thus, the ability to control the position of the square during the collision-avoidance reaction does affect the amplitude of the response. (B) The probability of landing is slightly reduced for open-loop presentations. (C) The latency of the collision-avoidance response is qualitatively similar for the closed- and open-loop stimuli, with slightly larger latencies in response to open-loop image expansion. (D) The open-loop landing response latencies were qualitatively similar to those seen during closed-loop presentations. Again, the latency is slightly shorter during closed-loop presentations. WBA, wing-beat amplitude.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1711143943\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;Open-loop versus closed-loop responses to image expansion. (A) During open-loop presentation the position of the square was controlled externally, as opposed to the closed-loop paradigm in which the fly maintains control over the position of the square. The closed-loop wing responses (filled circles) are repeated from Fig. 4. The open-loop responses (open circles), also generated in response to an expansion at a rate of 500\u0026#xB0; s-1, vary roughly with stimulus position as a square wave, in contrast to the open-loop responses, which vary sinusoidally. Thus, the ability to control the position of the square during the collision-avoidance reaction does affect the amplitude of the response. (B) The probability of landing is slightly reduced for open-loop presentations. (C) The latency of the collision-avoidance response is qualitatively similar for the closed- and open-loop stimuli, with slightly larger latencies in response to open-loop image expansion. (D) The open-loop landing response latencies were qualitatively similar to those seen during closed-loop presentations. Again, the latency is slightly shorter during closed-loop presentations. WBA, wing-beat amplitude.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 9.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F9.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 9.\u0022 src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F9.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F9.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 9.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F9.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1076133\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 9.\u003C\/span\u003E \n \u003Cp id=\u0022p-33\u0022 class=\u0022first-child\u0022\u003EOpen-loop \u003Cem\u003Eversus\u003C\/em\u003E closed-loop responses to image expansion. (A)\nDuring open-loop presentation the position of the square was controlled\nexternally, as opposed to the closed-loop paradigm in which the fly maintains\ncontrol over the position of the square. The closed-loop wing responses\n(filled circles) are repeated from \u003Ca id=\u0022xref-fig-4-6\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003EFig.\n4\u003C\/a\u003E. The open-loop responses (open circles), also generated in\nresponse to an expansion at a rate of 500\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E, vary roughly\nwith stimulus position as a square wave, in contrast to the open-loop\nresponses, which vary sinusoidally. Thus, the ability to control the position\nof the square during the collision-avoidance reaction does affect the\namplitude of the response. (B) The probability of landing is slightly reduced\nfor open-loop presentations. (C) The latency of the collision-avoidance\nresponse is qualitatively similar for the closed- and open-loop stimuli, with\nslightly larger latencies in response to open-loop image expansion. (D) The\nopen-loop landing response latencies were qualitatively similar to those seen\nduring closed-loop presentations. Again, the latency is slightly shorter\nduring closed-loop presentations. WBA, wing-beat amplitude.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-34\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F10\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F10.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022Comparison of the time course of responses for closed-loop and open-loop presentations. The changes in wing-beat amplitude (WBA) in response to a square expanding at 500\u0026#xB0; s-1 positioned between -140\u0026#xB0; and -120\u0026#xB0; followed a similar time course for open- and closed-loop presentations. The responses elicited by closed-loop presentation of the square were slightly smaller in magnitude than those in response to open-loop presentations. Closed-loop responses were taken from Fig. 3B; open-loop responses were taken from 5 flies in a manner analogous to the data plots in Fig. 3B.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1711143943\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;Comparison of the time course of responses for closed-loop and open-loop presentations. The changes in wing-beat amplitude (WBA) in response to a square expanding at 500\u0026#xB0; s-1 positioned between -140\u0026#xB0; and -120\u0026#xB0; followed a similar time course for open- and closed-loop presentations. The responses elicited by closed-loop presentation of the square were slightly smaller in magnitude than those in response to open-loop presentations. Closed-loop responses were taken from Fig. 3B; open-loop responses were taken from 5 flies in a manner analogous to the data plots in Fig. 3B.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 10.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F10.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 10.\u0022 src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F10.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F10.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 10.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F10.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1076115\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 10.\u003C\/span\u003E \n \u003Cp id=\u0022p-35\u0022 class=\u0022first-child\u0022\u003EComparison of the time course of responses for closed-loop and open-loop\npresentations. The changes in wing-beat amplitude (WBA) in response to a\nsquare expanding at 500\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E positioned between -140\u00b0 and\n-120\u00b0 followed a similar time course for open- and closed-loop\npresentations. The responses elicited by closed-loop presentation of the\nsquare were slightly smaller in magnitude than those in response to open-loop\npresentations. Closed-loop responses were taken from\n\u003Ca id=\u0022xref-fig-3-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F3\u0022\u003EFig. 3B\u003C\/a\u003E; open-loop responses\nwere taken from 5 flies in a manner analogous to the data plots in\n\u003Ca id=\u0022xref-fig-3-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F3\u0022\u003EFig. 3B\u003C\/a\u003E.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-36\u0022\u003EThe open- and closed-loop responses to a uniformly expanding object\ndemonstrate that image expansion is a sufficient stimulus for eliciting\ncollision-avoidance and landing responses in tethered flight. The amplitudes\nand latencies of these responses depend in part on both the position of the\nstimulus at the onset of expansion and the rate of expansion.\u003C\/p\u003E\n \u003C\/div\u003E\u003Cdiv class=\u0022section\u0022 id=\u0022sec-7\u0022\u003E\n \u003Ch2\u003EDiscussion\u003C\/h2\u003E\n \u003Cp id=\u0022p-37\u0022\u003EThe results indicate that an expanding object elicits both\ncollision-avoidance and landing responses in tethered \u003Cem\u003EDrosophila\u003C\/em\u003E.\nAlthough the same stimulus may elicit both behaviors, several observations\nsuggest that different pathways mediate the two reactions. First, the\nazimuthal position of the stimulus affects the expression of the two behaviors\nin different ways. For example, a fly generates its strongest\ncollision-avoidance reaction as a result of image expansion in the lateral\nportions of its visual field (Figs\n\u003Ca id=\u0022xref-fig-2-6\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003E2\u003C\/a\u003E,\u003Ca id=\u0022xref-fig-3-5\u0022 class=\u0022xref-fig\u0022 href=\u0022#F3\u0022\u003E3\u003C\/a\u003E,\u003Ca id=\u0022xref-fig-4-7\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003E4\u003C\/a\u003E,\u003Ca id=\u0022xref-fig-5-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F5\u0022\u003E5\u003C\/a\u003E),\nwhereas the probability of landing is greatest for stimuli in a frontal\nposition (Figs \u003Ca id=\u0022xref-fig-2-7\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003E2\u003C\/a\u003E,\n\u003Ca id=\u0022xref-fig-4-8\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003E4\u003C\/a\u003E,\n\u003Ca id=\u0022xref-fig-5-5\u0022 class=\u0022xref-fig\u0022 href=\u0022#F5\u0022\u003E5\u003C\/a\u003E). Second, although both\nresponses are most sensitive to rates of image expansion of approximately\n1000\u00b0 s\u003Csup\u003E-1\u003C\/sup\u003E, the collision-avoidance response is more broadly\ntuned, showing strong reactions for a greater range of image velocities than\nthe landing response (Figs \u003Ca id=\u0022xref-fig-5-6\u0022 class=\u0022xref-fig\u0022 href=\u0022#F5\u0022\u003E5\u003C\/a\u003E,\n\u003Ca id=\u0022xref-fig-6-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F6\u0022\u003E6\u003C\/a\u003E). Third, whereas the time\ncourse of the collision-avoidance response varies with rate of expansion\n(\u003Ca id=\u0022xref-fig-7-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F7\u0022\u003EFig. 7\u003C\/a\u003E), the time course of\nthe landing response remains constant. Fourth, the latency of the\ncollision-avoidance reaction maintains a relatively constant value of 50 ms\nfor different expansion velocities (\u003Ca id=\u0022xref-fig-8-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig.\n8\u003C\/a\u003E). In contrast, the delay before the onset of the landing\nresponse was larger than that of the collision-avoidance response (between\n100-300 ms) and shows a larger variation with rate of image expansion\n(\u003Ca id=\u0022xref-fig-8-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig. 8\u003C\/a\u003E). Finally, whereas the\nlanding response appears to represent a true fixed action pattern, the\ncollision-avoidance response is influenced by feedback. Removing the fly\u0027s\ncontrol over the position of the stimulus did not alter the time course of the\ncollision-avoidance reaction or the latency of either response, but did\nincrease the amplitude of the avoidance response for stimuli in caudolateral\npositions (Figs \u003Ca id=\u0022xref-fig-9-5\u0022 class=\u0022xref-fig\u0022 href=\u0022#F9\u0022\u003E9\u003C\/a\u003E,\n\u003Ca id=\u0022xref-fig-10-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F10\u0022\u003E10\u003C\/a\u003E).\u003C\/p\u003E\n \u003Cdiv id=\u0022sec-8\u0022 class=\u0022subsection\u0022\u003E\n \u003Ch3\u003EAre collision-avoidance reactions and torque spikes the\ntethered-flight analogs of free-flight saccades?\u003C\/h3\u003E\n \u003Cp id=\u0022p-38\u0022\u003EMany studies have described the rapid changes in wingstroke amplitude\n(sometimes referred to as `wing hitches\u0027) and the torque spikes generated\nduring tethered flight in \u003Cem\u003EDrosophila\u003C\/em\u003E\n(\u003Ca id=\u0022xref-ref-16-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-16\u0022\u003EG\u00f6tz et al., 1979\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-19-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-19\u0022\u003EHeide and G\u00f6tz, 1996\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-20-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-20\u0022\u003EHeisenberg and Wolf, 1979\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-21-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-21\u0022\u003EHeisenberg and Wolf, 1984\u003C\/a\u003E).\nSuperficially, the tethered-flight collision-avoidance reactions seem similar\nto free-flight saccades. Both are visually elicited responses and both direct\nthe fly away from approaching objects. Closer inspection of the two behaviors\nreveals important differences, however. Reconstructions of 3-dimensional\nfree-flight trajectories taken at 30 frames s\u003Csup\u003E-1\u003C\/sup\u003E suggest that the\nsaccades generated by \u003Cem\u003EDrosophila\u003C\/em\u003E are ballistic turns, lasting no\ngreater than 100 ms, during which a fly\u0027s heading is altered by 90\u00b0\n(\u003Ca id=\u0022xref-ref-30-5\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-30\u0022\u003ETammero and Dickinson, 2002\u003C\/a\u003E).\nIn contrast, the changes in wing stroke evoked by an expanding square in\ntethered flight last 600-700 ms (\u003Ca id=\u0022xref-fig-3-6\u0022 class=\u0022xref-fig\u0022 href=\u0022#F3\u0022\u003EFig.\n3\u003C\/a\u003E), roughly 12-14 times the length of a free-flight saccade. In\naddition, high-speed video recordings of free flying animals at 5000 frames\ns\u003Csup\u003E-1\u003C\/sup\u003E indicate that there is little change in the wing-beat amplitude\nduring the course of the saccades (S. Fry and M. H. Dickinson, unpublished\nobservations). This subtle alteration in wing kinematics is in contrast to the\nlarge and long-lasting change in left and right stroke amplitude during\ncollision-avoidance responses seen in tethered flight. The discrepancies in\nthe wing and body kinematics of tethered-flight collision-avoidance reactions\nand free-flight saccades question the assumption that the two are analogous.\nOne possible explanation for the differences between the tethered-flight\nreactions and free-flight saccades is that tethering a fly interrupts\nmechanosensory feedback from the halteres (gyroscopic sensors sensitive to\nangular velocities about the fly\u0027s roll, pitch and yaw axes)\n(\u003Ca id=\u0022xref-ref-8-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-8\u0022\u003EDickinson, 1999\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-27-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-27\u0022\u003ENalbach, 1993\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-28-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-28\u0022\u003ENalbach and Hengstenberg,\n1994\u003C\/a\u003E). Mechanosensory feedback from the halteres, antennae, the\nwings and other sensors during the initial stages of a saccade might serve a\ncritical role in turning off the motor program that alters wing kinematics,\nthus reducing the duration and magnitude of the saccade. Restoring some\nmechanosensory information by allowing a `loosely tethered\u0027 fly to rotate\nfreely about its yaw axis reduces the duration of a tethered saccade from 700\nto 250 ms (\u003Ca id=\u0022xref-ref-26-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-26\u0022\u003EMayer et al.,\n1988\u003C\/a\u003E).\u003C\/p\u003E\n \u003C\/div\u003E\n \u003Cdiv id=\u0022sec-9\u0022 class=\u0022subsection\u0022\u003E\n \u003Ch3\u003EVisual feedback during collision-avoidance reactions\u003C\/h3\u003E\n \u003Cp id=\u0022p-39\u0022\u003EPrevious studies have examined the role that visual feedback plays during\nthe course of a saccade. Spontaneously reversing the direction of displacement\nof a visual object increased the length of torque spikes, whereas doubling or\neliminating the displacement in the expected direction had little effect\n(Heisenberg and Wolf, \u003Ca id=\u0022xref-ref-20-3\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-20\u0022\u003E1979\u003C\/a\u003E,\n\u003Ca id=\u0022xref-ref-21-3\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-21\u0022\u003E1984\u003C\/a\u003E). These results suggest\nthat visual information alters the saccade only if the direction of motion is\nopposite to what is expected during the course of the torque spike. In our\nexperiments, the systematic variation in the amplitude of the\ncollision-avoidance response with the position of the square and the\ndifference between open- and closed-loop responses suggest that visual\nfeedback does play a role in regulating the size of the motor response. There\nare two possible explanations for variations in the size of the\ncollision-avoidance reaction. First, the fly\u0027s nervous system sends different\ncommands to the motor system in response to image expansion occurring at\ndifferent positions in the visual field, with the fly following these commands\nin a feed-forward maneuver. Alternatively, the nervous system might issue a\nsingle avoidance command and the variation in the response amplitude reflects\nthe role of sensory feedback. Removing the fly\u0027s control over the position of\nthe square by presenting the stimulus in open loop resulted in larger\nresponses (\u003Ca id=\u0022xref-fig-10-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F10\u0022\u003EFig. 10\u003C\/a\u003E),\nparticularly for positions at the rear of the fly\u0027s visual field. It is\nunlikely that the identical visual stimuli presented in similar locations\nduring our experiments would elicit different commands from the fly\u0027s nervous\nsystem. Although other sensory modalities, such as olfaction, might be able to\nmodify the command sent to the motor system, during our experiments each\npresentation was made under identical circumstances, thus minimizing any\neffects that other sensory modalities could have on the motor command. Because\nthe fly\u0027s collision-avoidance reaction causes the square to move to the rear\nof the fly\u0027s field of view, the expansion the fly experiences is reduced,\nleading to a smaller response. These results are consistent with prior\nobservations showing that free-flight saccades are slightly larger when the\nflies fly within a uniform visual panorama, compared to those generated in a\nrich-textured background (\u003Ca id=\u0022xref-ref-30-6\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-30\u0022\u003ETammero and\nDickinson, 2002\u003C\/a\u003E). Thus, our results are best explained by a model\nin which the motor response following a saccade command is modulated by\nfeedback from the visual and mechanosensory systems.\u003C\/p\u003E\n \u003C\/div\u003E\n \u003Cdiv id=\u0022sec-10\u0022 class=\u0022subsection\u0022\u003E\n \u003Ch3\u003EResponses to image expansion in other insects\u003C\/h3\u003E\n \u003Cp id=\u0022p-40\u0022\u003EAlthough collision-avoidance responses have not been previously reported in\ntethered flies, neurons sensitive to image expansion have been described in\nflies and other insects. Neurons sensitive to frontally positioned\napproximations of image expansion have been described in the cervical\nconnective of the blowfly \u003Cem\u003ECalliphora erythrocephala\u003C\/em\u003E, and are thought\nto play a role in generating the landing response\n(\u003Ca id=\u0022xref-ref-3-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-3\u0022\u003EBorst, 1991\u003C\/a\u003E). In the locust\n\u003Cem\u003ESchistocerca americana\u003C\/em\u003E, descending contralateral motion detector\ncells (DCMDs) may play a roll in collision-avoidance or escape behavior by\nfiring in response to looming objects\n(\u003Ca id=\u0022xref-ref-13-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-13\u0022\u003EGabbiani et al., 1999\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-17-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-17\u0022\u003EGray et al., 2001\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-23-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-23\u0022\u003EJudge and Rind, 1997\u003C\/a\u003E). In the\nlobula plate of the hawk moth \u003Cem\u003EManduca sexta\u003C\/em\u003E, two cells have been\nidentified that respond to looming stimuli. Class 1 cells respond to changes\nin the size of the looming object, and class 2 cells respond to an expanding\noptic flow field (\u003Ca id=\u0022xref-ref-35-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-35\u0022\u003EWicklein and Strausfeld,\n2000\u003C\/a\u003E). At present, there is no way of knowing whether the\nhomologues of any of these cells are responsible for the collision-avoidance\nbehavior, although the properties inferred from the behavior do suggest that\nthe \u003Cem\u003EDrosophila\u003C\/em\u003E cells represent a new class.\u003C\/p\u003E\n \u003C\/div\u003E\n \u003Cdiv id=\u0022sec-11\u0022 class=\u0022subsection\u0022\u003E\n \u003Ch3\u003EMechanisms underlying the collision-avoidance and landing\nresponses\u003C\/h3\u003E\n \u003Cp id=\u0022p-41\u0022\u003ETo detect the expanding square and trigger the collision-avoidance and\nlanding responses, flies might perform several different neural calculations.\nOne possibility is a `time-to-contact\u0027 model, where the fly calculates time\nbefore a collision with the square, and either saccades or extends its legs\nbefore the anticipated contact. A second possibility is a `temporal contrast\u0027\nmodel, in which the fly responds to darkening in its field of view.\nAlternatively, a fly may generate a response when the image across its retina\nsubtends a certain width or area, which we will refer to as a stimulus size\ntrigger. Finally, the fly might integrate image motion over space and time,\nwith saccade initiation occurring when the integral exceeds a threshold,\nreferred to as the `spatio-temporal integration model\u0027\n(\u003Ca id=\u0022xref-ref-2-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-2\u0022\u003EBorst, 1990\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-5-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-5\u0022\u003EBorst and Bahde, 1988\u003C\/a\u003E).\u003C\/p\u003E\n \u003Cp id=\u0022p-42\u0022\u003EThe time-to-contact model has been proposed as the trigger for deceleration\nbefore landing in freely flying \u003Cem\u003EDrosophila\u003C\/em\u003E\n(\u003Ca id=\u0022xref-ref-33-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-33\u0022\u003EWagner, 1982\u003C\/a\u003E). However, such\na calculation cannot be responsible for triggering the collision-avoidance\nresponse in our experiments, as the latency of the response is uniform for\nvarying rates of expansion, which approximate different approach speeds and\nthus different times-to-contact (\u003Ca id=\u0022xref-fig-8-5\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig.\n8\u003C\/a\u003E). Although landing-response latency does vary with expansion\nrate (\u003Ca id=\u0022xref-fig-8-6\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig. 8\u003C\/a\u003E), in other species\nof flies this latency also depends upon image contrast and size, factors that\nare inconsistent with the time-to-contact model\n(\u003Ca id=\u0022xref-ref-4-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-4\u0022\u003EBorst and Bahde, 1986\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-10-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-10\u0022\u003EEckert and Hamdorf, 1980\u003C\/a\u003E).\nDecreases in temporal contrast (i.e. darkening), coupled with object motion,\nevoke escape responses in stationary \u003Cem\u003EDrosophila\u003C\/em\u003E\n(\u003Ca id=\u0022xref-ref-22-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-22\u0022\u003EHolmqvist and Srinivasan,\n1991\u003C\/a\u003E; \u003Ca id=\u0022xref-ref-32-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-32\u0022\u003ETrimarchi and\nSchneiderman, 1995\u003C\/a\u003E). In our experiments, however, large changes in\ntemporal contrast, generated by instantaneous increases in the size of the\nsquare, elicited neither collision-avoidance nor landing responses\n(\u003Ca id=\u0022xref-fig-5-7\u0022 class=\u0022xref-fig\u0022 href=\u0022#F5\u0022\u003EFig. 5\u003C\/a\u003E). Cells that respond\nwhen an expanding object reaches a certain size have been described in locusts\n(Gabbiani et al., \u003Ca id=\u0022xref-ref-13-3\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-13\u0022\u003E1999\u003C\/a\u003E,\n\u003Ca id=\u0022xref-ref-14-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-14\u0022\u003E2001\u003C\/a\u003E) and hawk moths\n(\u003Ca id=\u0022xref-ref-35-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-35\u0022\u003EWicklein and Strausfeld,\n2000\u003C\/a\u003E). Such a model has also been suggested for\n\u003Cem\u003EDrosophila\u003C\/em\u003E (\u003Ca id=\u0022xref-ref-36-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-36\u0022\u003EWittekind,\n1988\u003C\/a\u003E), yet other investigators have demonstrated that larger flies\nwill land in response to sinusoidal gratings whose total size remains constant\n(\u003Ca id=\u0022xref-ref-4-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-4\u0022\u003EBorst and Bahde, 1986\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-34-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-34\u0022\u003EWehrhahn et al., 1981\u003C\/a\u003E). In our\nexperiments, response latency did not vary with expansion rate, as would be\nexpected if the response were triggered by an absolute stimulus size. Thus,\nthe stimulus-size model cannot account for our results. A model in which the\nspatially and temporally integrated output of local motion detectors exceed a\nthreshold to trigger a response has previously been proposed to account for\nlanding behavior in flies (\u003Ca id=\u0022xref-ref-2-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-2\u0022\u003EBorst,\n1990\u003C\/a\u003E), and remains the most parsimonious explanation for the\nbehavioral responses described here.\u003C\/p\u003E\n \u003C\/div\u003E\n \u003Cdiv id=\u0022sec-12\u0022 class=\u0022subsection\u0022\u003E\n \u003Ch3\u003EOptic flow model for saccade and landing response initiation\u003C\/h3\u003E\n \u003Cp id=\u0022p-43\u0022\u003EMany studies have emphasized the important role that optic flow plays in\nthe control of insect flight (\u003Ca id=\u0022xref-ref-7-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-7\u0022\u003ECollett et\nal., 1993\u003C\/a\u003E; \u003Ca id=\u0022xref-ref-24-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-24\u0022\u003EKrapp et al.,\n1998\u003C\/a\u003E; \u003Ca id=\u0022xref-ref-29-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-29\u0022\u003ESrinivasan,\n1993\u003C\/a\u003E). Flies are thought to estimate optic flow by means of a\nretinotopic array of motion detectors, each of which provides information on\nthe amplitude and direction of motion occurring over a small portion of a\nfly\u0027s visual field. By spatially integrating their inputs according to\nappropriate `matched filters\u0027, a fly receives feedback about its translational\nand rotational movement by spatially integrating responses from individual\nlocal motion detectors (\u003Ca id=\u0022xref-ref-12-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-12\u0022\u003EFranz and Krapp,\n2000\u003C\/a\u003E; \u003Ca id=\u0022xref-ref-24-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-24\u0022\u003EKrapp et al.,\n1998\u003C\/a\u003E). A model in which estimation of optic flow information is\nused to initiate collision-avoidance and landing responses is shown in\n\u003Ca id=\u0022xref-fig-11-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F11\u0022\u003EFig. 11\u003C\/a\u003E. Output from local\nmotion detectors is appropriately pooled, to measure image expansion occurring\nover different regions of the fly\u0027s visual world. Independent initiation of\nthe two behaviors requires that image expansion be calculated over at least\nthree different regions, the lateral left, lateral right, and frontal fields\nof view. Because the collision-avoidance reactions and landing responses are\ndiscrete events, both are likely to be triggered when some neural signal\nexceeds a threshold. Temporal integration of the expansion signal would allow\nthe input signal to accumulate even when the response of a hypothetical\nexpansion cell has reached a steady-state level. This allows the signal to\nexceed this threshold, while at the same time beneficially conditioning the\nsignal, making the input to the threshold detector less sensitive to high\nfrequency noise. This temporal integration must be `leaky\u0027, as the weak motion\nstimuli do not elicit responses (\u003Ca id=\u0022xref-ref-2-3\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-2\u0022\u003EBorst,\n1990\u003C\/a\u003E).\u003C\/p\u003E\n \u003Cp id=\u0022p-44\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F11\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F11.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022Model for eliciting collision-avoidance and landing responses. A fly estimates the optic flow experienced during flight using a two-dimensional array of motion detectors (i). Local motion information is then spatially pooled such that the image expansion in both the lateral and frontal fields of view is calculated (ii). The outputs of each of these three expansion calculations are then temporally integrated (iii) and passed through a threshold detector (iv). Expansion detected in a lateral field of view triggers a collision-avoidance response in the opposite direction, while frontal image expansion causes a landing response (v). Lateral expansion on one side inhibits the opposite expansion pathway, preventing a saccade from being immediately followed by another saccade in the opposite direction.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1711143943\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;Model for eliciting collision-avoidance and landing responses. A fly estimates the optic flow experienced during flight using a two-dimensional array of motion detectors (i). Local motion information is then spatially pooled such that the image expansion in both the lateral and frontal fields of view is calculated (ii). The outputs of each of these three expansion calculations are then temporally integrated (iii) and passed through a threshold detector (iv). Expansion detected in a lateral field of view triggers a collision-avoidance response in the opposite direction, while frontal image expansion causes a landing response (v). Lateral expansion on one side inhibits the opposite expansion pathway, preventing a saccade from being immediately followed by another saccade in the opposite direction.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 11.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F11.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 11.\u0022 src=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F11.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F11.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 11.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/jexbio\/205\/18\/2785\/F11.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1076117\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 11.\u003C\/span\u003E \n \u003Cp id=\u0022p-45\u0022 class=\u0022first-child\u0022\u003EModel for eliciting collision-avoidance and landing responses. A fly\nestimates the optic flow experienced during flight using a two-dimensional\narray of motion detectors (i). Local motion information is then spatially\npooled such that the image expansion in both the lateral and frontal fields of\nview is calculated (ii). The outputs of each of these three expansion\ncalculations are then temporally integrated (iii) and passed through a\nthreshold detector (iv). Expansion detected in a lateral field of view\ntriggers a collision-avoidance response in the opposite direction, while\nfrontal image expansion causes a landing response (v). Lateral expansion on\none side inhibits the opposite expansion pathway, preventing a saccade from\nbeing immediately followed by another saccade in the opposite direction.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-46\u0022\u003EThe longer latencies associated with the landing response when compared to\ncollision avoidance can be explained either by differences in visual\nprocessing or in the speed with which the motor system responds upon receiving\na descending command from the brain. It is unlikely that the longer latency of\nthe landing responses is due to slower activation of the motor system, as\nstudies on the flight initiation in \u003Cem\u003EDrosophila\u003C\/em\u003E demonstrate that the\ntibial levator muscle is activated as rapidly as 1-2 ms after activation of\nthe giant fiber (\u003Ca id=\u0022xref-ref-31-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-31\u0022\u003ETrimarchi and\nSchneiderman, 1993\u003C\/a\u003E). During visually elicited flight initiation,\nleg extension occurs approximately 20 ms after the presentation of the\nstimulus (\u003Ca id=\u0022xref-ref-32-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-32\u0022\u003ETrimarchi and Schneiderman,\n1995\u003C\/a\u003E). Additionally, the expansion-sensitive neurons in the\ncervical connective of the blowfly \u003Cem\u003ECalliphora erythrocephala\u003C\/em\u003E respond\nto bilateral image expansion with a latency between 100 and 200 ms\n(\u003Ca id=\u0022xref-ref-3-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-3\u0022\u003EBorst, 1991\u003C\/a\u003E), a value close to\nthe latency of the landing response in \u003Cem\u003EDrosophila\u003C\/em\u003E and \u003Cem\u003EMusca\u003C\/em\u003E\n(\u003Ca id=\u0022xref-ref-1-4\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-1\u0022\u003EBorst, 1986\u003C\/a\u003E). Thus, it is\nlikely that the longer latency in the initiation of the landing response\nreflects a difference in the time required for the spatial and temporal\nintegration of the visual signal, suggesting that separate circuits mediate\ndetection of the visual stimuli that trigger the collision-avoidance and\nlanding responses. The longer latency of the landing response as compared to\nthe collision-avoidance reaction may indicate either that a higher threshold\nlevel must be surpassed to trigger a response, or an increased amount of\nleakiness in the integrator preceding the threshold detectors in the landing\nsystem. Leakiness in the integrator can also explain the larger sensitivity of\nthe landing response latencies to expansion rate. Because it would be\nbehaviorally disastrous if a saccade in one direction was followed immediately\nby a saccade in the opposite direction, the output of the lateral expansion\ndetectors inhibits the opposite expansion pathway in our proposed model. Where\nin the collision-avoidance pathway this inhibition is manifested could not be\ndetermined by these experiments.\u003C\/p\u003E\n \u003Cp id=\u0022p-47\u0022\u003EIn our experiments, we varied only the azimuthal position of the expanding\nsquare. The center of the square was fixed along the equator of the fly\u0027s\nvisual field. If the elevation of the square changed from this position, it is\nunlikely that the output of the model would be changed, particularly when the\nhorizontal edges of the expanding object were on opposite sides of the equator\nof the fly\u0027s field of view. Our experiments did not examine the relative\nimportance of the vertical and horizontal components of the expansion.\nHowever, in a study of the landing response in the housefly \u003Cem\u003EMusca\ndomestica\u003C\/em\u003E, the directional sensitivity of the landing response was\ndependent on the position of the stimulus in the fly\u0027s visual field\n(\u003Ca id=\u0022xref-ref-34-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-34\u0022\u003EWehrhahn et al., 1981\u003C\/a\u003E). In\nthe frontal visual field above the equator, motion in the upward direction\ninitiated the landing response most strongly, whereas in the lateral visual\nfield at the equator, landing was most strongly initiated by front-to-back\nhorizontal motion. Our model, based upon the spatio-temporal integration of\noptic flow, would predict similar results.\u003C\/p\u003E\n \u003Cp id=\u0022p-48\u0022\u003EFurthermore, our model does not consider changes in response that might\noccur with multiple presentations of a stimulus. The landing response in\n\u003Cem\u003EDrosophila\u003C\/em\u003E does attenuate with multiple presentations\n(\u003Ca id=\u0022xref-ref-11-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-11\u0022\u003EFischbach, 1981\u003C\/a\u003E). We saw no\nattenuation in the collision-avoidance response during the course of our\nexperiments. One possibility is that the azimuthal position of the square\nvaried for each trial, preventing multiple repeated presentations in the same\nlocation. Even during the open-loop presentations, the azimuthal position of\nthe square varied randomly. However, during our experiments the square\nexpanded at approximately 5 s intervals, whereas in free flight visually\ninduced collision-avoidance saccades occur at intervals of 0.75-1.5 s\n(\u003Ca id=\u0022xref-ref-30-7\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-30\u0022\u003ETammero and Dickinson, 2002\u003C\/a\u003E)\nover flight trajectories lasting several minutes. Although decreasing the time\nbetween expansions while holding the position of the square constant might\nreveal some habituation, our experiments as presented did not result in\nnoticeable habituation, and thus this feature is not included in the\nmodel.\u003C\/p\u003E\n \u003C\/div\u003E\n \u003Cdiv id=\u0022sec-13\u0022 class=\u0022subsection\u0022\u003E\n \u003Ch3\u003EOptic-flow model and free-flight behavior\u003C\/h3\u003E\n \u003Cp id=\u0022p-49\u0022\u003EThe visual information that the fly receives from the expanding square in\nour experiments differs from what it would receive if it were freely flying\ntowards an object at a constant velocity. During our experiments, the square\nexpanded at a constant rate, which during free flight would result from the\nfly decelerating as it approached the object. Trajectories from free-flight\nexperiments have demonstrated that flies do decelerate as they approach the\nwalls of the arena (L. Tammero and M. Dickinson, unpublished data). However,\nthe stimulus used in our tethered experiments is only an approximation of the\nimage expansion experienced during free-flight object approach. Despite this,\nthe stimuli still reliably initiated both collision-avoidance and landing\nresponses. The theoretical model discussed previously would respond in a\nsimilar fashion to objects expanding at a constant rate as well as to objects\nwhose rate of expansion increased exponentially.\u003C\/p\u003E\n \u003Cp id=\u0022p-50\u0022\u003EDuring free flight, a fruit fly explores its environment using a series of\nstraight line segments interspersed with saccades\n(\u003Ca id=\u0022xref-ref-30-8\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-30\u0022\u003ETammero and Dickinson, 2002\u003C\/a\u003E).\nGiven that similar stimuli can evoke either a collision-avoidance response or\na landing response, how is it that these behaviors do not interfere with one\nanother in free flight? Reconstructing the fly\u0027s estimation of optic flow\nduring free flight suggested that image expansion in the frontolateral field\nof view precedes each saccade. Although in tethered flight, expansion in\nfrontolateral portions of the fly\u0027s field of view could elicit either a\nsaccade or a landing response, the latency before the onset of the saccade is\nshorter than the landing response latency. Thus, if a freely flying\n\u003Cem\u003EDrosophila\u003C\/em\u003E were to experience image expansion capable of eliciting\nboth a saccade and a landing response, the saccade is likely to occur first,\nsending the expanding image to the rear of the fly\u0027s field of view. During the\nperiod of straight flight following the saccade, our model predicts that the\nexpansion experienced by the fly builds until the next saccade is triggered. A\nlanding that terminates the flight trajectory could be elicited by image\nexpansion occurring in the central portion of the fly\u0027s field of view, or by\ninhibition of the fly\u0027s saccade pathways.\u003C\/p\u003E\n \u003Cp id=\u0022p-51\u0022\u003EIn free flight, the focus of expansion at which image velocity is zero\nshould reside in the fly\u0027s frontal visual field, assuming the animal\ntranslates while keeping its body axis tangent to its flight path and does not\nrotate. During the tethered-flight experiments, however, the\ncollision-avoidance responses were initiated by a square expanding in more\nlateral positions of the fly\u0027s visual field. For the image expansion reflexes\nidentified in these experiments to initiate saccades during free flight, the\nfocus of expansion must be displaced to a more lateral position in the visual\nfield. This lateral displacement may result from either rotation about the\nfly\u0027s yaw axis or side-slip. Alternatively, the collision-avoidance reflexes\nelicited by lateral expansion might represent circuitry that functions to\ndetect moving objects such as predators, whereas free-flight saccades elicited\nby the fly\u0027s approach to a static background might be initiated by separate\nreflexes not yet identified. High-resolution free-flight tracking, in which\nthe body orientation as well as the position of the fly is visualized, will be\nnecessary to differentiate between these two alternatives.\u003C\/p\u003E\n \u003Cp id=\u0022p-52\u0022\u003EImage expansion plays a central role in the initiation of landing responses\nand collision-avoidance reactions and, by extension, saccades. Variations in\nboth responses with the retinal location of image expansion, and differences\nin the latencies associated with visual processing, explain how the landing\nand collision-avoidance reactions interact during free flight. Because\nsaccades seem to be the prevalent means by which flies alter flight heading,\nthe initiation of these saccades plays a large role in controlling their\nflight behavior. Variations in the constituent elements of our conceptual\nmodel (such as the threshold levels or leakiness of the temporal integrator)\nwould necessarily be reflected by the animal\u0027s behavioral output. Thus, the\ncomputations using image expansion to land on and avoid approaching obstacles\nis a clear example of how patterns of behavior might emerge from interactions\nbetween the animal and its environment.\u003C\/p\u003E\n \u003C\/div\u003E\n \u003C\/div\u003E\u003Cdiv class=\u0022section ack\u0022 id=\u0022ack-1\u0022\u003E\u003Ch2\u003EACKNOWLEDGEMENTS\u003C\/h2\u003E\n \u003Cp id=\u0022p-53\u0022\u003EThe authors wish to thank Jocelyn Staunton and Jessica Choe for maintaining\nthe fly colonies. This work was supported by grants from the National Science\nFoundation (FD97-23424), ONR (FDN00014-99-1-0892) and Darpa\n(N00014-98-1-0855).\u003C\/p\u003E\n \u003C\/div\u003E\u003Cul class=\u0022copyright-statement\u0022\u003E\u003Cli class=\u0022fn\u0022 id=\u0022copyright-statement-1\u0022\u003E\u00a9 The Company of Biologists Limited\n2002\u003C\/li\u003E\u003C\/ul\u003E\u003Cdiv class=\u0022section ref-list\u0022 id=\u0022ref-list-1\u0022\u003E\u003Ch2\u003EReferences\u003C\/h2\u003E\u003Col class=\u0022cit-list ref-use-labels\u0022\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-1-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-1\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.1\u0022 data-doi=\u002210.1007\/BF00355543\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EBorst, A.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1986\u003C\/span\u003E). Time course of the\nhouseflies\u0027 landing response. \u003Cspan class=\u0022cit-source\u0022\u003EBiol Cybern.\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E54\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E379\u003C\/span\u003E\n-383.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DBiol%2BCybern.%26rft.volume%253D54%26rft.spage%253D379%26rft_id%253Dinfo%253Adoi%252F10.1007%252FBF00355543%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1007\/BF00355543\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-2-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-2\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.2\u0022 data-doi=\u002210.2307\/1311266\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EBorst, A.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1990\u003C\/span\u003E). How do flies land? From\nbehavior to neuronal circuits. \u003Cspan class=\u0022cit-source\u0022\u003EBioScience\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E40\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E292\u003C\/span\u003E\n-299.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DBioScience%26rft.volume%253D40%26rft.spage%253D292%26rft_id%253Dinfo%253Adoi%252F10.2307%252F1311266%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.2307\/1311266\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=A1990CW04500012\u0026amp;link_type=ISI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-newisilink cit-ref-sprinkles-webofscience\u0022\u003E\u003Cspan\u003EWeb of Science\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-3-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-3\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.3\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EBorst, A.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1991\u003C\/span\u003E). Fly visual interneurons\nresponsive to image expansion. \u003Cspan class=\u0022cit-source\u0022\u003EZool. Jb. Physiol.\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E95\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E305\u003C\/span\u003E\n-313.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DZool.%2BJb.%2BPhysiol.%26rft.volume%253D95%26rft.spage%253D305%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-4-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-4\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.4\u0022 data-doi=\u002210.1007\/BF00363978\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EBorst, A. and Bahde, S.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1986\u003C\/span\u003E). What kind of\nmovement detector is triggering the landing response of the housefly?\n\u003Cspan class=\u0022cit-source\u0022\u003EBiol. Cybern.\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E55\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E59\u003C\/span\u003E\n-69.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DBiol.%2BCybern.%26rft.volume%253D55%26rft.spage%253D59%26rft_id%253Dinfo%253Adoi%252F10.1007%252FBF00363978%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1007\/BF00363978\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=A1986E243600007\u0026amp;link_type=ISI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-newisilink cit-ref-sprinkles-webofscience\u0022\u003E\u003Cspan\u003EWeb of Science\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-5-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-5\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.5\u0022 data-doi=\u002210.1007\/BF00378023\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EBorst, A. and Bahde, S.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1988\u003C\/span\u003E).\nSpatio\u2014temporal integration of motion \u2014 a simple strategy of safe\nlanding in flies. \u003Cspan class=\u0022cit-source\u0022\u003ENaturwissenschaften\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E75\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E265\u003C\/span\u003E\n-267.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DNaturwissenschaften%26rft.volume%253D75%26rft.spage%253D265%26rft_id%253Dinfo%253Adoi%252F10.1007%252FBF00378023%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1007\/BF00378023\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=A1988N594700011\u0026amp;link_type=ISI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-newisilink cit-ref-sprinkles-webofscience\u0022\u003E\u003Cspan\u003EWeb of Science\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-6-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-6\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.6\u0022 data-doi=\u002210.1007\/BF01464710\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ECollett, T. S. and Land, M. F.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1975\u003C\/span\u003E). Visual\ncontrol of flight behavior in hoverfly, \u003Cem\u003ESyritta pipiens. \u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003EJ. Comp.\nPhysiol.\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E99\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E1\u003C\/span\u003E\n-66.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJ.%2BComp.%250APhysiol.%26rft.volume%253D99%26rft.spage%253D1%26rft_id%253Dinfo%253Adoi%252F10.1007%252FBF01464710%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1007\/BF01464710\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-7-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-7\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.7\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ECollett, T. S., Nalbach, H. O. and Wagner, H.\u003C\/strong\u003E\n(\u003Cspan class=\u0022cit-pub-date\u0022\u003E1993\u003C\/span\u003E). Visual stabilization in arthropods. \u003Cspan class=\u0022cit-source\u0022\u003ERev.\nOculomot. Res.\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E5\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E239\u003C\/span\u003E\n-263.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DReviews%2Bof%2Boculomotor%2Bresearch%26rft.stitle%253DRev%2BOculomot%2BRes%26rft.aulast%253DCollett%26rft.auinit1%253DT.%26rft.volume%253D5%26rft.spage%253D239%26rft.epage%253D263%26rft.atitle%253DVisual%2Bstabilization%2Bin%2Barthropods.%26rft_id%253Dinfo%253Apmid%252F8420551%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=8420551\u0026amp;link_type=MED\u0026amp;atom=%2Fjexbio%2F205%2F18%2F2785.atom\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-medline\u0022\u003E\u003Cspan\u003EPubMed\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-8-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-8\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.8\u0022 data-doi=\u002210.1098\/rstb.1999.0442\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EDickinson, M. H.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1999\u003C\/span\u003E). Haltere-mediated\nequilibrium reflexes of the fruit fly, \u003Cem\u003EDrosophila melanogaster.\u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003EPhil. Trans. R. Soc. Lond. B\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E354\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E903\u003C\/span\u003E\n-916.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DPhilosophical%2BTransactions%2Bof%2Bthe%2BRoyal%2BSociety%2BB%253A%2BBiological%2BSciences%26rft.stitle%253DPhil%2BTrans%2BR%2BSoc%2BB%26rft.issn%253D0080-4622%26rft.aulast%253DDickinson%26rft.auinit1%253DM.%2BH.%26rft.volume%253D354%26rft.issue%253D1385%26rft.spage%253D903%26rft.epage%253D916%26rft.atitle%253DHaltere-mediated%2Bequilibrium%2Breflexes%2Bof%2Bthe%2Bfruit%2Bfly%252C%2BDrosophila%2Bmelanogaster%26rft_id%253Dinfo%253Adoi%252F10.1098%252Frstb.1999.0442%26rft_id%253Dinfo%253Apmid%252F10382224%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Njoicm95cHRiIjtzOjU6InJlc2lkIjtzOjEyOiIzNTQvMTM4NS85MDMiO3M6NDoiYXRvbSI7czoyNDoiL2pleGJpby8yMDUvMTgvMjc4NS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003Cspan class=\u0022cit-sep cit-reflinks-variant-name-sep\u0022\u003E\/\u003C\/span\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-9-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-9\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.9\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EDickinson, M. H. and Lighton, J. R.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1995\u003C\/span\u003E).\nMuscle efficiency and elastic storage in the flight motor of \u003Cem\u003EDrosophila.\u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003EScience\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E128\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E82\u003C\/span\u003E\n-89.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-10-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-10\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.10\u0022 data-doi=\u002210.1007\/BF00657043\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EEckert, H. and Hamdorf, K.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1980\u003C\/span\u003E). Excitatory\nand inhibitory response components in the landing response of the blowfly,\n\u003Cem\u003ECalliphora erythrocephala. \u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003EJ. Comp. Physiol. A\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E138\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E253\u003C\/span\u003E\n-264.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJ.%2BComp.%2BPhysiol.%2BA%26rft.volume%253D138%26rft.spage%253D253%26rft_id%253Dinfo%253Adoi%252F10.1007%252FBF00657043%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1007\/BF00657043\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-11-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-11\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.11\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EFischbach, K. F.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1981\u003C\/span\u003E). Habituation and\nsensitization of the landing response of \u003Cem\u003EDrosophila melanogaster.\u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003ENaturwissenschaften\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E68\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E322\u003C\/span\u003E\n.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DNaturwissenschaften%26rft.volume%253D68%26rft.spage%253D322%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-12-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-12\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.12\u0022 data-doi=\u002210.1007\/s004220000163\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EFranz, M. O. and Krapp, H. G.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E2000\u003C\/span\u003E).\nWide-field, motion-sensitive neurons and matched filters for optic flow\nfields. \u003Cspan class=\u0022cit-source\u0022\u003EBiol. Cybern.\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E83\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E185\u003C\/span\u003E\n-197.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DBiological%2Bcybernetics%26rft.stitle%253DBiol%2BCybern%26rft.aulast%253DFranz%26rft.auinit1%253DM.%2BO.%26rft.volume%253D83%26rft.issue%253D3%26rft.spage%253D185%26rft.epage%253D197%26rft.atitle%253DWide-field%252C%2Bmotion-sensitive%2Bneurons%2Band%2Bmatched%2Bfilters%2Bfor%2Boptic%2Bflow%2Bfields.%26rft_id%253Dinfo%253Adoi%252F10.1007%252Fs004220000163%26rft_id%253Dinfo%253Apmid%252F11007295%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1007\/s004220000163\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=11007295\u0026amp;link_type=MED\u0026amp;atom=%2Fjexbio%2F205%2F18%2F2785.atom\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-medline\u0022\u003E\u003Cspan\u003EPubMed\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=000088867500003\u0026amp;link_type=ISI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-newisilink cit-ref-sprinkles-webofscience\u0022\u003E\u003Cspan\u003EWeb of Science\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-13-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-13\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.13\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EGabbiani, F., Krapp, H. G. and Laurent, G.\u003C\/strong\u003E\n(\u003Cspan class=\u0022cit-pub-date\u0022\u003E1999\u003C\/span\u003E). Computation of object approach object by a wide-field,\nmotion-sensitive neuron. \u003Cspan class=\u0022cit-source\u0022\u003EJ. Neurosci.\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E19\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E1122\u003C\/span\u003E\n-1141.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2BNeuroscience%26rft.stitle%253DJ.%2BNeurosci.%26rft.issn%253D0270-6474%26rft.aulast%253DGabbiani%26rft.auinit1%253DF.%26rft.volume%253D19%26rft.issue%253D3%26rft.spage%253D1122%26rft.epage%253D1141%26rft.atitle%253DComputation%2Bof%2BObject%2BApproach%2Bby%2Ba%2BWide-Field%252C%2BMotion-Sensitive%2BNeuron%26rft_id%253Dinfo%253Apmid%252F9920674%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Njoiam5ldXJvIjtzOjU6InJlc2lkIjtzOjk6IjE5LzMvMTEyMiI7czo0OiJhdG9tIjtzOjI0OiIvamV4YmlvLzIwNS8xOC8yNzg1LmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003Cspan class=\u0022cit-sep cit-reflinks-variant-name-sep\u0022\u003E\/\u003C\/span\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-14-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-14\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.14\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EGabbiani, F., Mo, C. and Laurent, G.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E2001\u003C\/span\u003E).\nInvariance of angular threshold computation in a wide-field looming-sensitive\nneuron. \u003Cspan class=\u0022cit-source\u0022\u003EJ. Neurosci.\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E21\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E314\u003C\/span\u003E\n-329.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2BNeuroscience%26rft.stitle%253DJ.%2BNeurosci.%26rft.issn%253D0270-6474%26rft.aulast%253DGabbiani%26rft.auinit1%253DF.%26rft.volume%253D21%26rft.issue%253D1%26rft.spage%253D314%26rft.epage%253D329%26rft.atitle%253DInvariance%2Bof%2BAngular%2BThreshold%2BComputation%2Bin%2Ba%2BWide-Field%2BLooming-Sensitive%2BNeuron%26rft_id%253Dinfo%253Apmid%252F11150349%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Njoiam5ldXJvIjtzOjU6InJlc2lkIjtzOjg6IjIxLzEvMzE0IjtzOjQ6ImF0b20iO3M6MjQ6Ii9qZXhiaW8vMjA1LzE4LzI3ODUuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003Cspan class=\u0022cit-sep cit-reflinks-variant-name-sep\u0022\u003E\/\u003C\/span\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-15-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-15\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.15\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EGoodman, L. J.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1960\u003C\/span\u003E). The landing responses of\ninsects. I. The landing response of the fly, \u003Cem\u003ELucilia sericata\u003C\/em\u003E, and\nother \u003Cem\u003ECalliphorinae. \u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003EJ. Exp. Biol.\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E37\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E854\u003C\/span\u003E\n-878.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2BExperimental%2BBiology%26rft.stitle%253DJ.%2BExp.%2BBiol.%26rft.issn%253D0022-0949%26rft.aulast%253DGOODMAN%26rft.auinit1%253DL.%2BJ.%26rft.volume%253D37%26rft.issue%253D4%26rft.spage%253D854%26rft.epage%253D878%26rft.atitle%253DThe%2BLanding%2BResponses%2Bof%2BInsects%253A%2BI.%2BThe%2BLanding%2BResponse%2Bof%2Bthe%2BFly%252C%2BLucilia%2BSericata%252C%2Band%2BOther%2BCalliphorinae%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NjoiamV4YmlvIjtzOjU6InJlc2lkIjtzOjg6IjM3LzQvODU0IjtzOjQ6ImF0b20iO3M6MjQ6Ii9qZXhiaW8vMjA1LzE4LzI3ODUuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-16-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-16\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.16\u0022 data-doi=\u002210.1007\/BF00337435\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EG\u00f6tz, K. G., Hengstenberg, B. and Biesinger, R.\u003C\/strong\u003E\n(\u003Cspan class=\u0022cit-pub-date\u0022\u003E1979\u003C\/span\u003E). Optomotor control of wing beat and body posture.\n\u003Cspan class=\u0022cit-source\u0022\u003EBiol. Cybern.\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E35\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E101\u003C\/span\u003E\n-112.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DBiol.%2BCybern.%26rft.volume%253D35%26rft.spage%253D101%26rft_id%253Dinfo%253Adoi%252F10.1007%252FBF00337435%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1007\/BF00337435\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=A1979HZ44200004\u0026amp;link_type=ISI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-newisilink cit-ref-sprinkles-webofscience\u0022\u003E\u003Cspan\u003EWeb of Science\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-17-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-17\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.17\u0022 data-doi=\u002210.1007\/s003590100182\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EGray, J. R., Lee, J. K. and Robertson, R. M.\u003C\/strong\u003E\n(\u003Cspan class=\u0022cit-pub-date\u0022\u003E2001\u003C\/span\u003E). Activity of descending contralateral movement detector\nneurons and collision avoidance behaviour in response to head-on visual\nstimuli in locusts. \u003Cspan class=\u0022cit-source\u0022\u003EJ. Comp. Physiol. A\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E187\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E115\u003C\/span\u003E\n-129.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2Bcomparative%2Bphysiology.%2BA%252C%2BNeuroethology%252C%2Bsensory%252C%2Bneural%252C%2Band%2Bbehavioral%2Bphysiology%26rft.stitle%253DJ%2BComp%2BPhysiol%2BA%2BNeuroethol%2BSens%2BNeural%2BBehav%2BPhysiol%26rft.aulast%253DGray%26rft.auinit1%253DJ.%2BR.%26rft.volume%253D187%26rft.issue%253D2%26rft.spage%253D115%26rft.epage%253D129%26rft.atitle%253DActivity%2Bof%2Bdescending%2Bcontralateral%2Bmovement%2Bdetector%2Bneurons%2Band%2Bcollision%2Bavoidance%2Bbehaviour%2Bin%2Bresponse%2Bto%2Bhead-on%2Bvisual%2Bstimuli%2Bin%2Blocusts.%26rft_id%253Dinfo%253Adoi%252F10.1007%252Fs003590100182%26rft_id%253Dinfo%253Apmid%252F15524000%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1007\/s003590100182\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=15524000\u0026amp;link_type=MED\u0026amp;atom=%2Fjexbio%2F205%2F18%2F2785.atom\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-medline\u0022\u003E\u003Cspan\u003EPubMed\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-18-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-18\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.18\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EHeide, G.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1983\u003C\/span\u003E). Neural mechanisms of flight\ncontrol in \u003Cem\u003EDiptera\u003C\/em\u003E. In \u003Cspan class=\u0022cit-source\u0022\u003EInsect Flight II\u003C\/span\u003E,\nBiona Report 2 (ed. W. Nachtigall), pp. \u003Cspan class=\u0022cit-fpage\u0022\u003E35\u003C\/span\u003E-52.\nStuttgart: G. Fischer.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-19-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-19\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.19\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EHeide, G. and G\u00f6tz, K. G.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1996\u003C\/span\u003E).\nOptomotor control of course and altitude in \u003Cem\u003EDrosophila melanogaster\u003C\/em\u003E\nis correlated with distinct activities of at least three pairs of flight\nsteering muscles. \u003Cspan class=\u0022cit-source\u0022\u003EJ. Exp. Biol.\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E199\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E1711\u003C\/span\u003E\n-1726.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2BExperimental%2BBiology%26rft.stitle%253DJ.%2BExp.%2BBiol.%26rft.issn%253D0022-0949%26rft.aulast%253DHeide%26rft.auinit1%253DG.%26rft.volume%253D199%26rft.issue%253D8%26rft.spage%253D1711%26rft.epage%253D1726%26rft.atitle%253DOptomotor%2Bcontrol%2Bof%2Bcourse%2Band%2Baltitude%2Bin%2BDrosophila%2Bmelanogaster%2Bis%2Bcorrelated%2Bwith%2Bdistinct%2Bactivities%2Bof%2Bat%2Bleast%2Bthree%2Bpairs%2Bof%2Bflight%2Bsteering%2Bmuscles.%26rft_id%253Dinfo%253Apmid%252F8708578%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NjoiamV4YmlvIjtzOjU6InJlc2lkIjtzOjEwOiIxOTkvOC8xNzExIjtzOjQ6ImF0b20iO3M6MjQ6Ii9qZXhiaW8vMjA1LzE4LzI3ODUuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003Cspan class=\u0022cit-sep cit-reflinks-variant-name-sep\u0022\u003E\/\u003C\/span\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-20-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-20\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.20\u0022 data-doi=\u002210.1007\/BF00611046\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EHeisenberg, M. and Wolf, R.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1979\u003C\/span\u003E). On the fine\nstructure of yaw torque in visual flight orientation of \u003Cem\u003EDrosophila\nmelanogaster. \u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003EJ. Comp. Physiol. A\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E130\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E113\u003C\/span\u003E\n-130.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJ.%2BComp.%2BPhysiol.%2BA%26rft.volume%253D130%26rft.spage%253D113%26rft_id%253Dinfo%253Adoi%252F10.1007%252FBF00611046%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1007\/BF00611046\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-21-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-21\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.21\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EHeisenberg, M. and Wolf, R.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1984\u003C\/span\u003E).\u003Cspan class=\u0022cit-source\u0022\u003E\u003Cem\u003EVision in\u003C\/em\u003E Drosophila\u003C\/span\u003E\n. Berlin:\nSpringer-Verlag.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-22-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-22\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.22\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EHolmqvist, M. H. and Srinivasan, M. V.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1991\u003C\/span\u003E).\nA visually evoked escape response of the housefly. \u003Cspan class=\u0022cit-source\u0022\u003EJ. Comp.\nPhysiol. A\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E169\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E451\u003C\/span\u003E\n-459.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2Bcomparative%2Bphysiology.%2BA%252C%2BNeuroethology%252C%2Bsensory%252C%2Bneural%252C%2Band%2Bbehavioral%2Bphysiology%26rft.stitle%253DJ%2BComp%2BPhysiol%2BA%2BNeuroethol%2BSens%2BNeural%2BBehav%2BPhysiol%26rft.aulast%253DHolmqvist%26rft.auinit1%253DM.%2BH.%26rft.volume%253D169%26rft.issue%253D4%26rft.spage%253D451%26rft.epage%253D459%26rft.atitle%253DA%2Bvisually%2Bevoked%2Bescape%2Bresponse%2Bof%2Bthe%2Bhousefly.%26rft_id%253Dinfo%253Apmid%252F1779418%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=1779418\u0026amp;link_type=MED\u0026amp;atom=%2Fjexbio%2F205%2F18%2F2785.atom\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-medline\u0022\u003E\u003Cspan\u003EPubMed\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-23-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-23\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.23\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EJudge, S. J. and Rind, F. C.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1997\u003C\/span\u003E). The locust\nDCMD, a movement-detecting neurone tightly tuned to collison trajectories.\n\u003Cspan class=\u0022cit-source\u0022\u003EJ. Exp. Biol.\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E200\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E2209\u003C\/span\u003E\n-2216.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2BExperimental%2BBiology%26rft.stitle%253DJ.%2BExp.%2BBiol.%26rft.issn%253D0022-0949%26rft.aulast%253DJudge%26rft.auinit1%253DS.%26rft.volume%253D200%26rft.issue%253D16%26rft.spage%253D2209%26rft.epage%253D2216%26rft.atitle%253DThe%2Blocust%2BDCMD%252C%2Ba%2Bmovement-detecting%2Bneurone%2Btightly%2Btuned%2Bto%2Bcollision%2Btrajectories%26rft_id%253Dinfo%253Apmid%252F9320123%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NjoiamV4YmlvIjtzOjU6InJlc2lkIjtzOjExOiIyMDAvMTYvMjIwOSI7czo0OiJhdG9tIjtzOjI0OiIvamV4YmlvLzIwNS8xOC8yNzg1LmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003Cspan class=\u0022cit-sep cit-reflinks-variant-name-sep\u0022\u003E\/\u003C\/span\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-24-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-24\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.24\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EKrapp, H. G., Hengstenberg, B. and Hengstenberg, R.\u003C\/strong\u003E\n(\u003Cspan class=\u0022cit-pub-date\u0022\u003E1998\u003C\/span\u003E). Dendritic structure and receptive-field organization of\noptic flow processing interneurons in the fly. \u003Cspan class=\u0022cit-source\u0022\u003EJ.\nNeurophysiol.\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E79\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E1902\u003C\/span\u003E\n-1917.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2BNeurophysiology%26rft.stitle%253DJ.%2BNeurophysiol.%26rft.issn%253D0022-3077%26rft.aulast%253DKrapp%26rft.auinit1%253DH.%2BG.%26rft.volume%253D79%26rft.issue%253D4%26rft.spage%253D1902%26rft.epage%253D1917%26rft.atitle%253DDendritic%2BStructure%2Band%2BReceptive-Field%2BOrganization%2Bof%2BOptic%2BFlow%2BProcessing%2BInterneurons%2Bin%2Bthe%2BFly%26rft_id%253Dinfo%253Apmid%252F9535957%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Mjoiam4iO3M6NToicmVzaWQiO3M6OToiNzkvNC8xOTAyIjtzOjQ6ImF0b20iO3M6MjQ6Ii9qZXhiaW8vMjA1LzE4LzI3ODUuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003Cspan class=\u0022cit-sep cit-reflinks-variant-name-sep\u0022\u003E\/\u003C\/span\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-25-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-25\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.25\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ELehmann, F.-O. and Dickinson, M. H.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1997\u003C\/span\u003E). The\nchanges in power requirements and muscle efficiency during elevated force\nproduction in the fruit fly \u003Cem\u003EDrosophila. \u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003EJ. Exp. Biol.\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E200\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E1133\u003C\/span\u003E\n-1143.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2BExperimental%2BBiology%26rft.stitle%253DJ.%2BExp.%2BBiol.%26rft.issn%253D0022-0949%26rft.aulast%253DLehmann%26rft.auinit1%253DF.%2BO.%26rft.volume%253D200%26rft.issue%253D7%26rft.spage%253D1133%26rft.epage%253D1143%26rft.atitle%253DThe%2Bchanges%2Bin%2Bpower%2Brequirements%2Band%2Bmuscle%2Befficiency%2Bduring%2Belevated%2Bforce%2Bproduction%2Bin%2Bthe%2Bfruit%2Bfly%2BDrosophila%2Bmelanogaster.%26rft_id%253Dinfo%253Apmid%252F9131808%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NjoiamV4YmlvIjtzOjU6InJlc2lkIjtzOjEwOiIyMDAvNy8xMTMzIjtzOjQ6ImF0b20iO3M6MjQ6Ii9qZXhiaW8vMjA1LzE4LzI3ODUuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003Cspan class=\u0022cit-sep cit-reflinks-variant-name-sep\u0022\u003E\/\u003C\/span\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-26-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-26\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.26\u0022 data-doi=\u002210.1007\/BF00604014\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EMayer, M., Vogtmann, K., Bausenwein, B., Wolf, R. and\nHeisenberg, M.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1988\u003C\/span\u003E). Flight control during `free yaw turns\u0027\nin \u003Cem\u003EDrosophila melanogaster. \u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003EJ. Comp. Physiol. A\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E163\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E389\u003C\/span\u003E\n-399.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJ.%2BComp.%2BPhysiol.%2BA%26rft.volume%253D163%26rft.spage%253D389%26rft_id%253Dinfo%253Adoi%252F10.1007%252FBF00604014%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1007\/BF00604014\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-27-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-27\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.27\u0022 data-doi=\u002210.1007\/BF00212693\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ENalbach, G.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1993\u003C\/span\u003E). The halteres of the blowfly\n\u003Cem\u003ECalliphora\u003C\/em\u003E 1. Kinematics and dynamics. \u003Cspan class=\u0022cit-source\u0022\u003EJ. Comp. Physiol.\nA\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E173\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E293\u003C\/span\u003E\n-300.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJ.%2BComp.%2BPhysiol.%250AA%26rft.volume%253D173%26rft.spage%253D293%26rft_id%253Dinfo%253Adoi%252F10.1007%252FBF00212693%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1007\/BF00212693\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=A1993MA06600004\u0026amp;link_type=ISI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-newisilink cit-ref-sprinkles-webofscience\u0022\u003E\u003Cspan\u003EWeb of Science\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-28-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-28\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.28\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ENalbach, G. and Hengstenberg, R.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1994\u003C\/span\u003E). The\nhalteres of the blowfly \u003Cem\u003ECaliphora\u003C\/em\u003E 2. Three-dimensional organization\nof compensatory reactions to real and simulated rotations. \u003Cspan class=\u0022cit-source\u0022\u003EJ. Comp.\nPhysiol. A\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E175\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E695\u003C\/span\u003E\n-708.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJ.%2BComp.%250APhysiol.%2BA%26rft.volume%253D175%26rft.spage%253D695%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-29-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-29\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.29\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ESrinivasan, M. V.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1993\u003C\/span\u003E). How insects infer\nrange from visual motion. \u003Cspan class=\u0022cit-source\u0022\u003ERev. Oculomot. Res\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E5\u003C\/span\u003E, \u003Cspan class=\u0022cit-fpage\u0022\u003E139\u003C\/span\u003E-156.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DReviews%2Bof%2Boculomotor%2Bresearch%26rft.stitle%253DRev%2BOculomot%2BRes%26rft.aulast%253DSrinivasan%26rft.auinit1%253DM.%2BV.%26rft.volume%253D5%26rft.spage%253D139%26rft.epage%253D156%26rft.atitle%253DHow%2Binsects%2Binfer%2Brange%2Bfrom%2Bvisual%2Bmotion.%26rft_id%253Dinfo%253Apmid%252F8420547%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=8420547\u0026amp;link_type=MED\u0026amp;atom=%2Fjexbio%2F205%2F18%2F2785.atom\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-medline\u0022\u003E\u003Cspan\u003EPubMed\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-30-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-30\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.30\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ETammero, L. F. and Dickinson, M. H.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E2002\u003C\/span\u003E). The\ninfluence of visual landscape on the free flight behavior of the fruit fly\n\u003Cem\u003EDrosophila melanogaster. \u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003EJ. Exp. Biol.\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E205\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E327\u003C\/span\u003E\n-343.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2BExperimental%2BBiology%26rft.stitle%253DJ.%2BExp.%2BBiol.%26rft.issn%253D0022-0949%26rft.aulast%253DTammero%26rft.auinit1%253DL.%2BF.%26rft.volume%253D205%26rft.issue%253D3%26rft.spage%253D327%26rft.epage%253D343%26rft.atitle%253DThe%2Binfluence%2Bof%2Bvisual%2Blandscape%2Bon%2Bthe%2Bfree%2Bflight%2Bbehavior%2Bof%2Bthe%2Bfruit%2Bfly%2BDrosophila%2Bmelanogaster%26rft_id%253Dinfo%253Apmid%252F11854370%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NjoiamV4YmlvIjtzOjU6InJlc2lkIjtzOjk6IjIwNS8zLzMyNyI7czo0OiJhdG9tIjtzOjI0OiIvamV4YmlvLzIwNS8xOC8yNzg1LmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003Cspan class=\u0022cit-sep cit-reflinks-variant-name-sep\u0022\u003E\/\u003C\/span\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-31-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-31\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.31\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ETrimarchi, J. R. and Schneiderman, A. M.\u003C\/strong\u003E\n(\u003Cspan class=\u0022cit-pub-date\u0022\u003E1993\u003C\/span\u003E). Giant fiber activation of an intrinsic muscle in the\nmesothoracic leg of \u003Cem\u003EDrosophila melanogaster. \u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003EJ. Exp.\nBiol.\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E177\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E149\u003C\/span\u003E\n-167.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2BExperimental%2BBiology%26rft.stitle%253DJ.%2BExp.%2BBiol.%26rft.issn%253D0022-0949%26rft.aulast%253DTrimarchi%26rft.auinit1%253DJ.%2BR.%26rft.volume%253D177%26rft.issue%253D1%26rft.spage%253D149%26rft.epage%253D167%26rft.atitle%253DGiant%2Bfiber%2Bactivation%2Bof%2Ban%2Bintrinsic%2Bmuscle%2Bin%2Bthe%2Bmesothoracic%2Bleg%2Bof%2BDrosophila%2Bmelanogaster%26rft_id%253Dinfo%253Apmid%252F8486998%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NjoiamV4YmlvIjtzOjU6InJlc2lkIjtzOjk6IjE3Ny8xLzE0OSI7czo0OiJhdG9tIjtzOjI0OiIvamV4YmlvLzIwNS8xOC8yNzg1LmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003Cspan class=\u0022cit-sep cit-reflinks-variant-name-sep\u0022\u003E\/\u003C\/span\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-32-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-32\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.32\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ETrimarchi, J. R. and Schneiderman, A. M.\u003C\/strong\u003E\n(\u003Cspan class=\u0022cit-pub-date\u0022\u003E1995\u003C\/span\u003E). Initiation of flight in the unrestrained fly,\n\u003Cem\u003EDrosophila melanogaster. \u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003EJ. Zool., Lond.\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E235\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E211\u003C\/span\u003E\n-222.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJ.%2BZool.%252C%2BLond.%26rft.volume%253D235%26rft.spage%253D211%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-33-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-33\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.33\u0022 data-doi=\u002210.1038\/297147a0\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EWagner, H.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1982\u003C\/span\u003E). Flow-field variables trigger\nlanding in flies. \u003Cspan class=\u0022cit-source\u0022\u003ENature\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E297\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E147\u003C\/span\u003E\n-148.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DNature%26rft.volume%253D297%26rft.spage%253D147%26rft_id%253Dinfo%253Adoi%252F10.1038%252F297147a0%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1038\/297147a0\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-34-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-34\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.34\u0022 data-doi=\u002210.1007\/BF00335364\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EWehrhahn, C., Hausen, K. and Zanker, J.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1981\u003C\/span\u003E).\nIs the landing response of the housefly (\u003Cem\u003EMusca\u003C\/em\u003E) driven by motion of a\nflow field? \u003Cspan class=\u0022cit-source\u0022\u003EBiol. Cybern.\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E41\u003C\/span\u003E, \u003Cspan class=\u0022cit-fpage\u0022\u003E91\u003C\/span\u003E-99.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DBiol.%2BCybern.%26rft.volume%253D41%26rft.spage%253D91%26rft_id%253Dinfo%253Adoi%252F10.1007%252FBF00335364%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1007\/BF00335364\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-35-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-35\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.35\u0022 data-doi=\u002210.1002\/1096-9861(20000821)424:2\u0026lt;356::AID-CNE12\u0026gt;3.0.CO;2-T\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EWicklein, M. and Strausfeld, N. J.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E2000\u003C\/span\u003E).\nOrganization and significance of neurons that detect change of visual depth in\nthe hawk moth \u003Cem\u003EManduca sexta. \u003C\/em\u003E\u003Cspan class=\u0022cit-source\u0022\u003EJ. Comp. Neurol.\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E424\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E356\u003C\/span\u003E\n-376.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DThe%2BJournal%2Bof%2Bcomparative%2Bneurology%26rft.stitle%253DJ%2BComp%2BNeurol%26rft.aulast%253DWicklein%26rft.auinit1%253DM.%26rft.volume%253D424%26rft.issue%253D2%26rft.spage%253D356%26rft.epage%253D376%26rft.atitle%253DOrganization%2Band%2Bsignificance%2Bof%2Bneurons%2Bthat%2Bdetect%2Bchange%2Bof%2Bvisual%2Bdepth%2Bin%2Bthe%2Bhawk%2Bmoth%2BManduca%2Bsexta.%26rft_id%253Dinfo%253Adoi%252F10.1002%252F1096-9861%252820000821%2529424%253A2%253C356%253A%253AAID-CNE12%253E3.0.CO%253B2-T%26rft_id%253Dinfo%253Apmid%252F10906708%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1002\/1096-9861(20000821)424:2\u0026lt;356::AID-CNE12\u0026gt;3.0.CO;2-T\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10906708\u0026amp;link_type=MED\u0026amp;atom=%2Fjexbio%2F205%2F18%2F2785.atom\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-medline\u0022\u003E\u003Cspan\u003EPubMed\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=000088442200012\u0026amp;link_type=ISI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-newisilink cit-ref-sprinkles-webofscience\u0022\u003E\u003Cspan\u003EWeb of Science\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-36-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-36\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-205.18.2785.36\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EWittekind, W. C.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1988\u003C\/span\u003E). The landing response\nof tethered flying \u003Cem\u003EDrosophila\u003C\/em\u003E is induced at a critical object angle.\n\u003Cspan class=\u0022cit-source\u0022\u003EJ. Exp. Biol.\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E135\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E491\u003C\/span\u003E\n-493.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJ.%2BExp.%2BBiol.%26rft.issn%253D0022-0949%26rft.volume%253D135%26rft.spage%253D491%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003C\/ol\u003E\u003C\/div\u003E\u003Cspan class=\u0022highwire-journal-article-marker-end\u0022\u003E\u003C\/span\u003E\u003C\/div\u003E\u003Cspan id=\u0022related-urls\u0022\u003E\u003C\/span\u003E\u003C\/div\u003E\u003Ca href=\u0022https:\/\/jeb.biologists.org\/content\/205\/18\/2785.abstract\u0022 class=\u0022hw-link hw-link-article-abstract\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EView Abstract\u003C\/a\u003E\u003C\/div\u003E \u003C\/div\u003E\n\n \n \u003C\/div\u003E\n\u003Cdiv class=\u0022panel-separator\u0022\u003E\u003C\/div\u003E\u003Cdiv class=\u0022panel-pane pane-highwire-article-trendmd\u0022 \u003E\n \n \n \n \u003Cdiv class=\u0022pane-content\u0022\u003E\n \u003Cdiv id=\u0022trendmd-suggestions\u0022\u003E\u003C\/div\u003E \u003C\/div\u003E\n\n \n \u003C\/div\u003E\n\u003C\/div\u003E\n \u003C\/div\u003E\n\u003C\/div\u003E\n\u003C\/div\u003E\u003Cscript type=\u0022text\/javascript\u0022 src=\u0022https:\/\/jeb.biologists.org\/sites\/default\/files\/js\/js_EMKkw3mpop79zEawKCE1avNSIh9glowpJsMezNZG6Cw.js\u0022\u003E\u003C\/script\u003E\n\u003C\/body\u003E\u003C\/html\u003E"}